2 Is a Theory of Argument Possible

Reading this chapter in 2017, I am struck by its length, which seems excessive, and also by my selection of authors covered. The name ‘John McPeck’ is largely forgotten in philosophical circles today. When I was working on this material, his claims about informal logic and critical thinking posed a significant challenge, both pedagogically and theoretically.

Would critical thinking not be something different for different subjects? McPeck claimed it would. If so, how could philosophers – even formal logicians – be justified in their claims to teach it? If informal logic was about good and bad arguments, wouldn’t standards of assessment similarly vary from one subject to another? Again, the question posed a pedagogical challenge. As for theory, on McPeck’s view there would be nothing general to be said. Those interested in critical thinking and informal logic were not inclined to accept these challenges, but felt pressed to respond. My own response is here. McPeck derived some of his views from Stephen Toulmin, whose work on argument structure and appraisal is still studied and used today. Looking back, I would have done better to discuss Toulmin’s account, as distinct from that of McPeck. But I did not. Current versions of discipline-specificity have been developed in detail by Mark Weinstein.

The theme of deductivism retains its temptations. I still resist deductivism and would still insist that the fact that a reconstructed argument is clear and cogent does not mean that it is an accurate version of something else. We need to distinguish between the clarity of a reconstructed argument and its accuracy as a rendition of the unreconstructed version. It remains tempting not to do so. Recently, I find deductivism more common in application than in professed theory. As was the case decades ago, deductivism is still used as an ad hoc presumption to resolve questions about missing premises.

As to Stephen Thomas, a search revealed that his text Practical Reasoning in Natural Language, went into many editions. There may have been seven. The fourth edition (1997) was several hundred pages longer than the first one. I never met Stephen Thomas or heard him speak. The idea of a spectrum theory, wherein the inference aspect of argumentation can be appraised as having degrees of strength, was innovative in its time and retains some interest and plausibility.

My notion here of what a theory of argument should include began in a traditional way: one would need an account of various legitimate (and illegitimate) types of inference and of conditions of premise acceptability. These beginnings would seem too narrow today; their narrowness in fact emerged even as I explored them in the mid eighties. I was led to consider broader aspects: principles of interpretation and criticism; relations between principles of interpretation and standards of assessment, and between arguers and their audiences. More recent writings on the theory of argument extend into these and broader themes of discourse, rationality, and rhetoric. Noteworthy is Harald Wohlrapp’s The Concept of Argument: A Philosophical Foundation (German 2008, English 2014).

Except in certain limited circles, there is no recognized subject called ‘the theory of argument’. Yet there are clearly a number of questions about arguing and argument not answered by formal logic and of considerable importance. A theory of argument would discuss the nature and purpose of argument and specify and defend standards for the appraisal of arguments. It would specify how many different types of arguments there are and what standards are appropriate to assess each type. It would explain when and why it is reasonable to read into discourse claims that are not explicitly stated, and whether and how the personalities and beliefs of arguers and audiences logically affect the merits of argumentation. Ideally a theory of argument would apply to all natural arguments. But is there, or could there be, any such thing as a theory of argument?

Although there have been works on the theory of argument and calls for such theory in some circles, many remain sceptical about the quest. They regard the theory of argument as a non-subject, unless it is identified with the formal study of valid and invalid inference patterns. Such a response – either there is nothing general to be said about arguments or what there is to be said is formal and the proper subject of formal logic – was common among philosophers some years back and still persists in some quarters. We are used to thinking of the study of argument as being primarily a matter of logic, and of logic as being primarily formal; hence the call for a nonformal theory of argument may seem novel or contrived. However, such questions as ‘How many different types of arguments are there?’, ‘When and why should we regard an argument as having unstated premises?’, and ‘Is the truth of premises too strong a requirement for soundness of argumentation?’, cannot be answered by formal techniques. To respond to them, we need observation, reasoning, the justification of normative standards, and philosophical theorizing.

1. Against the Idea of a Theory of Argument

In his book Critical Thinking and Education, philosopher and educational theorist John McPeck contends that the very notion of a nonformal theory of argument is a non-starter. Referring to a suggestion that the pedagogy and theory of informal logic and critical thinking would be immensely aided by the development of a theory of argument, McPeck says:

We might ask what it would be like to have a general theory of ordinary argument or reasoning. For one thing, the theory would provide a set of rules or principles to which we could appeal in the evaluation of arguments. But if informal logicians were ever successful at developing all these rules and principles, they would then have a formal logic of ordinary argument or reasoning: that is, the desired theory would vitiate the informal dimension of their reasoning and render their enterprise a bonafide logic, which could then be taught as the formal logic of ordinary reasoning.¹

According to McPeck, there could not be a nonformal theory of argument, because any general account we could produce would be formal.

To sort out McPeck’s view it is necessary to distinguish between a more general and a more specific sense of the key word ‘formal’.² The word ‘formal’ may mean ‘systematic, well-ordered, having universal or general scope’. In this sense, a theory of argument would surely be a formal theory, just as theories in ethics, political philosophy, and epistemology are (in this sense) formal theories. However, there is no problem about informal logicians developing a theory of argument which is in this broad sense formal. The incompatibility between informal logical principles and a formal theory emerges only when we consider a more specific and narrower sense of ‘formal’, that which is intended when we describe such systems as C.I. Lewis’ S5, or an axiomatized version of number theory as formal systems. Formal systems have clearly stated rules, definite criteria for well-formed strings or formulae, and axioms to serve as the basis for derivations. They are written in technical, not natural, languages. As formal systems they are not, strictly speaking, about anything; they may be given one or more interpretations. If a formal theory of argument were formal in this sense, that would indeed be incompatible with what informal logicians have been saying about arguments. They have been saying that formal systems do not cover all the topics we need to raise in discussing natural language arguments, and that many such topics bring in nonformal questions about context and substance.

Informal logicians, contesting the drive for complete rigor and purity among formalists, contend that the appraisal of natural arguments requires something other than translation into a technical formal language and application of formal rules to test validity. However, it is only in the narrower sense of ‘formal’ that informal logicians deny that a theory of natural argument will be a formal theory. Nothing precludes the development, within informal logic, of a theory of argument that is formal in the broader sense.

McPeck’s claim that informal logicians would vitiate themselves and ‘go formal’ if they ever managed to develop a theory of argument is based on a failure to distinguish these two senses of ‘formal’. McPeck has, in effect, conflated the general and the formal.³ A perfectly general principle might be formulated, handling such an issue as when an arguer’s personal reliability is relevant to the acceptability of his or her premises. Such a principle would not be formal in the sense of being in an artificial language or of being an axiom or rule in a formal system, but could nevertheless be part of a general theory of argument.⁴

As it occurs in ‘formal logic’, the word ‘formal’ usually has the second, narrow meaning explained above. In this sense of ‘formal’ there is no more reason to believe that the principles of a theory of argument would be formal than there is to believe that the principles of moral, political, or epistemological theories would be formal. That is to say, there is no reason at all to believe this.

Since logic has for so long been regarded both as intrinsically formal and as the science or art of argument, the move from ‘it’s a general theory of argument’ to ‘it’s a formal theory of argument’ may seem enticing and plausible. But it has no more force than the analogous move for moral or scientific theories; that means that it has no force.

In fact, theories of argument that are, in the requisite sense, nonformal are more than possible. They are actual. Although many philosophers seem to hold that the theory of argument is a non-subject, many others (and some of the same ones) hold philosophical theories of argument to which they frequently appeal for pedagogical and other purposes. Some popular theories are inadequate in various ways. There is an unfortunate tendency to state such theories in a few words and go on to appeal to them as the basis for other work. So far, theories of argument have been more epigrammatic than thoughtful.

2. Are Argument Standards Discipline-Specific?

Though he contends in Critical Thinking and Education that there can be no such thing as a nonformal theory of argument, John McPeck in fact states a nonformal theory of argument in that same work. He puts forward a discipline-specific theory in which the understanding and evaluation of arguments is left as a task for particular academic disciplines. This theory maintains that the premises and inferences of all natural arguments are properly assessed only by reference to the standards of one or more specific disciplines. Standards for sound argumentation may vary from one discipline to another, according to this theory. There are as many types of good arguments (at least) as there are disciplines. Any attempt to develop general, cross-disciplinary standards of argument is misguided. A good argument in physics satisfies standards quite different from those which are applicable to a good argument in law or in history. Evaluating arguments requires critical thinking and critical thinking amounts to a judicious, reflective scepticism which must be based on a sound knowledge of the inner workings of a particular area of thought.

McPeck proposes his discipline-specific theory as follows:

Since critical thinking is always critical thinking about X, it follows that critical thinking is intimately connected with other fields of knowledge. Thus the criteria for the judicious use of scepticism are supplied by the norms and standards of the field under consideration.⁵

Just as the rules of a particular game do not necessarily apply to other games, so certain principles of reason apply within some sphere of human experience but not in others. A principle of reason in business or law, for example, might be fallacious in science or ethics. This is neither surprising nor profound but it is a point that is continually obscured by informal logicians and it may explain their optimism about the development of a general theory of argument.⁶

The existing disciplines are already steeped in their own reasoning procedures, fallible as they might be at times. But learning to use those procedures properly involves learning the idiosyncrasies of those disciplines. ⁷

McPeck is led to a discipline-specific theory partly by a study of Stephen Toulmin’s works and partly by the idea – expressed in the first passage quoted above – that arguments deal with specific subjects and each specific subject is located within some discipline or other. His presupposition here is, apparently, that the norms come from the subject matter.

Toulmin wrote an early book, The Uses of Argument, decrying the dominance of formal logic in argument analysis. He urged that there were many diverse types of argument appropriate to diverse human activities. Several decades later, he followed his early monograph with a text, coauthored with Richard Rieke and Allan Janik.⁸ The text echoes the earlier theory. However, it does impose a common structure on argumentation. Each argument has, according to Toulmin, a claim (what standard analysis would call the conclusion), a ground or grounds for the claim (in standard accounts, the premises), and a warrant and backing. The warrant is a general proposition linking the grounds and claim and the backing is comprised of other claims that can be used to back up the warrant. For example, a simple argument such as ‘you shouldn’t smoke because you might get lung cancer’ would be seen as having ‘you might get lung cancer’ as the ground and ‘you shouldn’t smoke’ as the claim. The warrant, which must be constructed and read into the argument, would be something like ‘Smoking often causes lung cancer’. The backing would be found in the medical theories which support belief in the warrant.

Toulmin emphasizes the important role of disciplinary knowledge and procedures in the understanding and appraisal of argument. Thus it is in some sense natural that McPeck should appeal to his account for support.

In another way, however, what Toulmin says is not consistent with what McPeck wants to say. Oddly enough, in view of Toulmin’s strong dissent from traditional logical approaches, his analysis commits him to imposing a common structure on all arguments. They will all have the same modus ponens form, when the warrant is supplied. And yet there are cases where the fit is rather unnatural. Even in the simple example about smoking, for instance, we have to restrict ourselves to backing and warrant from one field in order to make Toulmin’s style of analysis fit. Why not supplement the medical evidence with a claim about obligations not to unnecessarily risk one’s health and a backing from canons of ethics or prudence? If we did this, we would immediately have an argument to which at least two ‘disciplines’ were relevant.

Despite some rather dramatic statements to the contrary, Toulmin is in fact committed to the belief that there are many general points about argument structure and evaluation which are correctly super-imposed (as it were) on the standards of the various disciplines. This makes his account an unpromising source for a view such as McPeck’s, which disclaims any possibility of general standards working across disciplines.

The reception of Toulmin’s ideas on argument is itself a matter of some interest. His ideas have been roundly rejected by most philosophers and yet have gained wide acceptance in other circles, notably among scholars of argumentation whose background is in rhetoric or communication, rather than logic and philosophy. Nevertheless, an examination of several recent accounts of Toulmin’s theory seems to indicate that the philosophers’ rejection was on solid grounds.

In an excellent and thorough review of Toulmin’s text, Ralph Johnson worked hard with his theory and eventually decided that it faced serious problems.

Many of the warrants Toulmin cites as examples do not seem to belong to any identifiable field. But this only raises another problem. What is to count as a field? Law and science qualify, of course. Does astrology? Does common sense? Does philosophy? And what happens when, as is often enough the case, an arguer provides grounds from different fields?⁹

Arguments in which several distinct grounds are offered at once and each ground comes from a different ‘field’ are very common in everyday life, and yet Toulmin’s model does not seem to apply to them.

F.H. van Eemeren, R. Grootendorst, and T. Kruiger, offer a thorough analysis of Toulmin’s work in their book The Study of Argumentation. They offer many criticisms, among them the following, regarding Toulmin’s positing of four essential elements in argument (claim, ground, warrant, and backing) instead of the traditional two (premises and conclusion):

In fact, however, he assumes in his model that the data (grounds) are accepted at face value; if this is not the case, then, he says, it will have to be made the case by way of a preliminary argument. Then the datum from the one argument will be the claim in the other. There is absolutely no reason why the same should not apply to the warrant. If a warrant is not immediately accepted as authoritative, then an attempt must be made to remove the objections to it by means of another argument, in which the warrant from the first argument appears as the claim. And if an argument contains a backing for the warrant, then in fact there are two arguments.¹⁰

At this point it should be clear that no solid basis for McPeck’s theory can be found in Toulmin’s theory.

The other line of thought that leads McPeck to a discipline-specific theory is equally unconvincing. He reasons that since every argument and every thought are about some specific thing, and since every specific thing is properly understood within some specific discipline, every argument is properly assessed only with reference to the standards of some specific discipline. This argument is glaringly incomplete, as reviewers of McPeck’s book were quick to note.¹¹ The opening premise is obviously uncontroversial. Surely all thought is about some subject. You cannot just think, without thinking about some thing or other. However, it does not follow that that something or other is appropriately located in some one academic discipline. Also, from the fact that thought must be about an object, we certainly are not entitled to conclude that standards for appraising that thought fall into the one specific discipline (in which the object is located).

McPeck gives no good grounds for his view that arguments fall into distinct disciplines and that only these disciplines can offer the proper tools for their understanding and evaluation.

Even if we were to grant McPeck’s assumption that arguments fall into disciplines, those disciplines might very well employ common standards of reasoning. Indeed, this is what philosophers and others have commonly supposed. McPeck obviously dissents from this view but he nowhere gives a sufficient logical, epistemic, or psychological basis for his dissent. In response to critics, McPeck has indicated that the philosophical background for his view is to be found in Wittgenstein and should be understood as an adaptation of Wittgenstein’s notion of forms of life. But such a reference offers poor logical support, given the notorious slipperiness of this Wittgensteinian notion. McPeck seems so convinced of the discipline dependence of argument analysis that he simply assumes that there are no common standards of reasoning in different disciplines.

A discipline-specific theory of argument can be stated in more or less radical versions. If the theory insists only that in order to evaluate the premises of arguments, we need information, which will come from various different disciplines, then it is relatively uncontroversial. No logician formal or informal – has ever denied this first view of what it means to be discipline-specific. None has ever seriously claimed that logic alone could supply the necessary tools to determine the truth or acceptability of the premises of arguments, and few would be so bold as to maintain that logic gives you all you need to be a critical thinker.¹² Presumably McPeck does not mean only to claim this first view that some extra-logical information is needed for the evaluation of arguments; otherwise he would not be so strongly objecting to the theory of argument as a general subject. More significantly, a discipline-specific theory might state a second view to the effect that some judgments about the merits of some inferences can only be made from within specific disciplines. That qualified claim is suggested when McPeck says ‘a principle of reason in business or law, for example, might be fallacious in science of ethics.’ Most radical would be a third view, according to which all appraisal of both premises and reasoning depends on standards which are developed by, and only intelligible within, the particular disciplines. On this third view there would be no such thing as a good analogy or invalid syllogism as such. There would be good analogies-within-psychology, invalid conditional arguments-within-law, and so on.

McPeck’s major pedagogical claim is that attempts to improve reasoning and critical thinking by offering separate courses in either formal or informal logic are misguided, as they presume false theories of reasoning and argument. The uses to which McPeck seeks to put his view, and the supplementary comments he makes about it, require that he endorse the third and most radical version of discipline-specificity. It is only on this version that the idea of teaching generally applicable standards of argument appraisal would cease to make sense. The major purpose of McPeck’s book is to make a point about educating people to think critically. He contends that it is not possible to do this by teaching formal logic, informal logic, or critical thinking as distinct subjects. The correct way to do it, he says, is to teach the separate academic disciplines in an epistemically alert way so as to cultivate in students a judicious scepticism that is appropriate to whatever particular subject is being studied. McPeck’s account combines a theory of argument with a pedagogical theory of critical thinking. The first view holds nothing novel. If McPeck were to hold only the qualified second view he would have to admit that there could be many useful and important cross-disciplinary standards for good argument and that these might fruitfully be taught in critical thinking courses that were generally about good and poor reasoning. This view would not support McPeck’s strong pedagogical claims. He needs the third view.

No one would dispute the first view. Indeed, typically argument premises cannot be assessed without the particular knowledge which often comes from specific disciplines. This obvious truth does not entail that a discipline-specific theory of argument is true, however; it says nothing about types of arguments, types of inference, means of appraising inference, and so on. The second view says something about some arguments, and issues a warning that we should not expect standards to transfer automatically from one area to another. This modest version of the discipline-specific theory may be correct. It does not preclude either the possibility of standards that apply to most arguments, or the existence of general categories of classification which would transcend disciplinary boundaries. It is possible, for instance, that this second view should be true and that the third view is false. Such patterns as modus ponens, analogies, syllogisms, and inductive generalizations are found in a wide variety of contexts and disciplines, and should be assessed from the same standpoint, using the same rules, whenever they occur.

The third view, which amounts to a radical discipline-specific theory of argument, is simply not plausible. First of all, not every subject fits neatly into one and only one academic discipline. An argument about nuclear weapons development, for instance, might very well include both psychological considerations about the likely reactions of an enemy to a strategy and financial considerations regarding the comparative costs of conventional and nuclear weapons. Indeed, discussions of issues pertaining to nuclear weapons quite commonly draw from politics, history, military strategy, ethics, and engineering, as well as psychology and economics. Many issues are like this one, and many arguments about them do not fit well into a neat framework of established academic fields or disciplines.

The point was put humorously by Perry Weddle, who said in a review of McPeck’s book:

… Recall One Week in the Life of the Typical Educated Person. Five to ten hours reading the newspaper: There was the case of Ariel Sharon, a cartoon depicting Reagan as Western gunslinger confronting Andropov, an editorial defending multiple-choice exams for teachers. There were stock market tips, astrological counsel and advice on health via vegetarian diets. That’s just a small sample, of course, … This week the Typical Educated Person has to find a new mechanic, listen to the broker, advise a friend’s child on her career, choose toilet paper, decide whether to fight an undemocratic harsh but fair administrative decision, to trouble-shoot a malfunctioning vacuum cleaner, to turn down a thoughtful and appreciated invitation to spend the weekend at Mendocino. The Typical Educated Person argued politics, music, psychology, sports, religion … Academic fields cover only a fraction of such stuff.¹³

A discipline-specific theory of argument will be hard to apply in practice because it will require us to sort arguments in a way that is most unfaithful to action discussion, decision-making, and debate.

There are also more theoretical arguments against discipline-specific standards of argumentation and reasoning. Even if we could put every argument in its own disciplinary cubby-hole, we cannot guarantee that existing academic disciplines as we presently understand them accurately reflect the ontology of the real world in the ways in which they divide and categorize objects and problems.

A discipline-specific theory of argument such as the third version, which is so radical as to claim that all the important standards of argument appraisal are specific to the various academic disciplines, is simply implausible. In many respects, various disciplines at least appear to employ common standards of reasoning at a number of significant points. In all disciplines, we find a concern for consistency; the need to rely on testimony some of the time and an attendant concern to distinguish reliable from unreliable testimony; the need to deduce further conclusions from explicitly stated knowledge; occasional uses of analogies; and many other apparently similar logical features. It is possible that in some subtle ways the appraisal of testimony is logically different in history, physics, and law. But such a claim has not been shown even for one aspect of argumentation, and it is highly unlikely that it would be true for all.

The continuity and co-ordination of distinct disciplines during some periods of history and with reference to some specific topics would be hard to account for if each discipline had its own standards of reasoning, so embedded within the discipline that they could not be ‘detached’ and applied to discussions within other disciplines. So too would the tradition of successful external criticism of disciplinary practices.

For all these reasons the discipline-specific theory in the strong form advocated by McPeck has small claim to be a descriptively accurate theory of argument. Nor is it normatively appealing, because it is implicitly uncritical and conservative. If existing disciplines are to provide us with the only standards appropriate to use for the assessment of argument, then it will be impossible to give a good argument for the conclusion that the standards of any one of these disciplines are flawed. This is a counter-intuitive result that leaves too little room for rational criticism of disciplinary practice. In addition, it is untrue to the actual history of thought. Strong criticism of disciplines both from within and without is a prominent feature of the actual history of academic subjects.

In short, a radical discipline-specific theory of argument is not tenable. It will pose many problems of application; it does not offer a natural description of the phenomena of argument; and it is normatively too weak.

3. Are All Good Arguments Deductively Valid?

Another theory of argument, more popular among philosophers than the discipline-specific theory, is the deductivist theory. According to this theory, there is no need to sort arguments by discipline, for there is fundamentally only one type of (good) argument. A good argument must be deductively valid: the premises must entail the conclusion. In a good argument, it is logically impossible for the conclusion to be false provided that the premises are true. Furthermore, the premises are true. Because the argument is deductively valid, the true premises provide full and sufficient reasons for the conclusion, and thus justify it. Thus good arguments should serve the purpose of convincing an audience that a conclusion is true. All good arguments are as tight and firm as proofs in mathematics. They are comparable to ‘All men are mortal; Justin Trudeau is a man; therefore Justin Trudeau is mortal’, in that true premises are stated, and provide compelling, conclusive support for a conclusion. Any argument not meeting these conditions is logically inconclusive and, as failing to meet these standards, logically worthless.

Many logicians – both formal and informal – endorse a deductivist theory of argument. These theorists are aware that most naturally occurring arguments fail to be deductively valid as stated. Few wish to draw the conclusion that most naturally occurring arguments are worthless. To avoid this consequence, deductivists often urge that many naturally occurring arguments are enthymemes. They need to be ‘filled in’ with premises that were unstated by the arguer. Many naturally occurring arguments can be filled in with true or plausible premises in such a way that the amended set of premises entails the conclusion; they thereby qualify as inferentially good arguments on the deductivist theory.

In a paper on deductivism published in 1970, D. Stove reported being unable to find any explicit statements or defenses of the theory, which he nevertheless claimed was a basic tacit assumption of many philosophers.¹⁴ Stove argued in great detail that Hume was a deductivist, in order to show that the critique of the theory presented in his article had some real application. Presently, statements of deductivism are rather easy to find in texts and other sources. Here is one from a text on formal logic, by Karel Lambert and William Ulrich. (Lambert and Ulrich do not purport to cover informal logic in the text; however they do purport to eliminate it as a legitimate subject of study.) They say:

An argument is sound if and only if (1) it is valid and (2) all its premises are true. An inference is sound just in case the argument representing it is sound.¹⁵

This is a classic statement. Further explanation in the text makes it clear that Lambert and Ulrich understand ‘valid’ to mean ‘deductively valid in virtue of form’.¹⁶ That is, the premises would have to entail the conclusion, and the entailment relationship would have to hold in virtue of the structure of the argument, as based on standardly logical words such as ‘all’, ‘some’, ‘none’, ‘not’, ‘if then’, ‘and’, ‘or’, and so on.

Formal deductivism would have it that all good arguments are deductively valid in virtue of their logical form; nonformal deductivism that they are deductively valid in virtue either of meaning or of form. It is often important to distinguish between formalist and nonformalist versions of deductivism. Lambert and Ulrich do not clarify this distinction. However, the points made here apply to both versions, so the distinction will be ignored for the moment. In the simple deductively valid argument ‘Joan has a cousin; therefore Joan has a parent who has a sibling’, validity is due to the meaning of ‘cousin’, ‘parent’ and so on, not to logical form. This argument is deductively valid in virtue of the meaning of such terms, and not in virtue of its logical form.

The central claim of deductivism is that anything less than a relation of entailment between premises and conclusion is unsatisfactory. On this theory there are no degrees or kinds of logical support. Lambert and Ulrich’s statement of deductivism also includes a condition that premises must satisfy: they must be true. This condition has been questioned as too strong; but we shall skirt that issue at the moment and consider only those aspects of deductivism that concern the classification of arguments and the appraisal of inferences.¹⁷

Lambert and Ulrich’s book is a text on formal logic. But deductivism is not restricted to formalist circles. Deductivist views are also to be found in texts on informal logic, as we see in Gerald Nosich, Reasons and Arguments:

Truth and validity are two basic concepts in logical analysis because, for an argument to be sound (to prove its conclusion), it must be both valid and have true premises. Moreover, if you have a valid argument and all of its premises are true, you have proved the conclusion. When it comes right down to it, validity and truth of the premises are all there is to a good argument.¹⁸

Challenging the view, Carl Wellman’s book, Challenge and Response, has this to say about deductivism:

Deduction is that form of reasoning in which the claim is made that the conclusion follows necessarily from the premises. If it is possible for all the premises to be true and the conclusion false, then the argument is invalid; if the truth of the premises is a sufficient condition for the truth of the conclusion, then the argument is valid. It is deductive reasoning that has been the traditional subject matter of logic. Deductivism is the view that this is the only form of reasoning. If so, and if only reasoning can justify any statement, then clearly all justification is by deduction. The obvious question to ask is what reason there is to accept deductivism.¹⁹

Although deductivism is stated by Wellman as a theory about reasoning and not a theory about arguments, the move from one to the other is immediate, in context. If all arguments are based on reasoning, and all reasoning is deductive, then all arguments are based on deductive reasoning. Wellman states deductivism in order to criticize it. He does not hold this theory himself. He believes, rather, that there are many plausible natural arguments which it does not readily apply and he objects to the way in which premises have to be added in order to make some of these naturally occurring arguments deductively valid.

Stove distinguishes two senses of conclusiveness for arguments. Arguments are positively conclusive if the premises would give a completely rational being some positive degree of belief in the conclusion, and they are absolutely conclusive if they would give such a being as great a degree of belief in the conclusion as there is for the premises. An argument is absolutely irrational if the premises would add no support whatever to the conclusion.²⁰ With this apparatus, Stove defines deductivism as the thesis that all deductively invalid arguments are absolutely irrational. Stove then goes on to point out that deductivism entails the epistemic equivalence of ‘All of the ten flames observed in the past have been hot, so the next flame observed will be hot’ and ‘All of the one million flames observed in the past have been hot, so the next flame observed will be hot.’ It entails that these two arguments are equally, and absolutely, irrational. The extremity of this conclusion implied by deductivism makes Stove fear he is addressing a straw man. But as he points out, the rather common philosophical practice of showing an argument to be invalid and then inferring immediately that no further criticism of it is needed, does presuppose deductivism in just this extreme form.

3a. Deductivism as a Simple Theory

Deductivism has the advantage of being an extremely simple theory of argument. On this theory, there is only one type of argument; therefore there is no need to sort or classify arguments and to develop criteria for doing so. Problems regarding examples that do not fit tidily into the requisite classificatory categories do not arise: there is only one category. There is only one type of argument, deductive, and only one standard for appraising the quality of the inferential aspect of arguments. This requirement all arguments will have to satisfy. In systems of formal logic there are clearly articulated standards for formal deductive validity. If deductivism is the correct theory of argument, we have the assured relevance of an established and recognized body of precise knowledge, applicable to all arguments.

This simplicity comes at a cost, however. There are alternate ways of paying. One way is to face the consequence Stove spells out so clearly: all invalid arguments are equally and totally flawed. Since most arguments in empirical science and in ordinary life are not, as stated, deductively valid, this theory will leave the deductivist in a radically sceptical position. Indeed, if we have no view as to how the accumulation of empirical evidence can rationally support hypotheses, it is a mystery as to how we can ever generate the premises that are needed for deductively valid arguments. This difficulty was emphasized by John Stuart Mill and, in a different way, by Sextus Empiricus.

Most contemporary deductivists will not pay such a high price and prefer instead to borrow in the currency of reconstruction. Recognizing that most natural arguments are not deductive as stated, they regard such arguments as incomplete. To apply their theory in a plausible and non-sceptical way to naturally occurring arguments, they reconstruct them, seeing them as having tacit premises not spelled out by the arguer. Arguments in law, ethics, administration, empirical science, literary criticism, and ordinary life do not look like the watertight proofs of mathematics. As stated, they are rarely deductively valid. To avoid the conclusion that they are all equally and absolutely ‘irrational’, these arguments are regarded as enthymematic. This approach is surely preferable to the radically sceptical and counterintuitive consequence of applying the theory literally to unreconstructed natural arguments. Nevertheless, it too is costly.

The pro-and-con situation in which we find ourselves with many issues does not naturally fit a deductivist account, which makes the merit of an argument an all-or-nothing affair. When a natural argument is supplemented, and thereby rendered deductively valid, the added premises are regarded as ‘missing’. The deductivist will say that they were implicit in the original argument, but left unstated for one reason or another. Perhaps they were too obvious to mention and recognized as such by the arguer and the audience. Perhaps they were controversial and deliberately omitted. Perhaps they were omitted simply because the arguer lacked a perfect ‘deductive sense’ and didn’t understand that they were required to make the argument valid.

The deductivist who wishes to avoid radical scepticism about naturally occurring arguments has no problem classifying arguments and no problem deciding which inferential standard to apply to which argument. He does, however, have to face quite a task reconstructing natural arguments. Since few arguments, as stated, are deductively valid, a deductivist who seeks to avoid scepticism is committed to a ‘reading-in’ policy which is extensive. This involves labor, but that is the least of the problems.

A major challenge lies in the fact that any argument can be supplemented with extra premises in such a way as to make it deductively valid. In fact, some texts advise students to do this. If all else fails, an argument can be made deductively valid by adding a premise of the form ‘If (P, Q, R, J) then C’, where P, Q, R and J are the stated premises and C is the conclusion. The added statement is a conditional with the stated premises, conjoined, as the antecedent and the conclusion as the consequent. Such a statement is commonly referred to as the associated conditional.²¹ To some this reiterative procedure seems a mere subterfuge, but to others it appears a natural manoeuvre – quite legitimate. An associated conditional can always be formed, and a determined theorist can always insist that it was implicit in the argument. A major problem with this view, though, is that for every naturally occurring argument there is such an available associated conditional. There is, then, always a way to make an argument deductively valid, whether or not it was valid in its unreconstructed form.²²

3b. Deductivism and Missing Premises

Though preferable to literal deductivism the reconstructivist approach is cumbersome and, for that reason, objectionable. In many cases it also appears to misrepresent the character of the original argument. There are reasons, surely, why arguments from observation and experience have been characterized historically as different in degree of conclusiveness from the deductive arguments of geometry and mathematics. Even if we consider a ridiculous argument, such as ‘Roses are red; violets are blue; therefore Ed loves Sue’, we can render it deductively valid. We just add a premise ‘If roses are red and violets are blue, Ed loves Sue’, and insist that this associated conditional was implicit, but unstated, in the original. The addition is reiterative in that it merely repeats the original argument, turning it into a conditional statement that links the premises with the conclusion. If one acknowledges a problem with simple reiteration, one can avoid it by generalizing on this reiterative condition. For instance, one could instead regard ‘If some flowers are coloured, then all people called Ed love all people called Sue’ as the unstated premise.

There is always a way to make any argument deductively valid by adding premises. Furthermore there is always more than one way. If you don’t like merely reiterating the whole argument, you can choose from countless prospective premises which will entail the reiterative conditional statement. Literal deductivism has the consequence that almost all arguments in empirical science, scholarly endeavor and ordinary life are absolutely worthless. But reconstructive deductivism, unless very elaborately qualified, will have the consequence that they are all absolutely worthy, from an inferential point of view.²³ This consequence emerges because any argument can easily be rendered valid, and the reconstructive thrust behind this theory commits us to regarding the content of argument as largely indeterminate.

Despite the prominence of reconstructive deductivism as a theory of argument and despite its compatibility with significant elements of logical theory and pedagogy, it ultimately runs counter to strong traditions in logic. One such tradition is that there are nonconclusive but nevertheless reasonable arguments, especially in empirical science. Another is that there are fallacies. A fallacy is an error in reasoning.²⁴ Fallacies in the logical sense are not mistaken assumptions or beliefs; they are errors in reasoning. For fallacies in this sense to exist, people must sometimes make mistakes in inferring conclusions from premises. But on this common understanding of ‘fallacy’, there will be no fallacies for the deductivist, because every argument that is not deductively valid as stated is to be made deductively valid by reconstruction. This result will not be welcome.²⁵

Deductivism makes a distorting lens through which to examine the phenomena of natural argument. It recommends too much revision of the data to save the theory. The problem is not that there exist arguments that cannot be reconstructed on a deductivist model. Rather, it is that although it is often quite easy to read into natural arguments extra premises so as to render them deductively valid, the procedure of doing so is frequently merely reiterative and, if not that, ad hoc.

Reconstructive deductivism allows and requires us to do too much to the data. If we look at the world through purple glasses, it will appear purple, but little is proven by such observations. Similarly, if we look at people’s arguments through deductivist spectacles, all arguments will appear as complete or incomplete deductions. But little that is real is seen through these spectacles. We need some good reason as to why this is the right way to look at arguments. Apart from simplicity, the only one seems to be the question-begging insistence that in a good argument premises must suffice to prove the conclusion, where by ‘suffice to prove’, ‘deductively entail’ is implicitly meant. But this view is contestable and, in the context, question-begging.

4. Degrees of Validity? Degrees of Support?

We move now to another theory of argument, the spectrum theory. This theory is not nearly so common as deductivism. Nor has it yet been thoroughly developed by philosophers. It is found only in scattered statements – oral and written – by some who have paid close attention to the analysis of naturally occurring arguments. According to the spectrum theory, the strength of the connection between the premises and conclusion of an argument is susceptible to degrees. There are tighter and looser connections. The deductive connection is the tightest, but it is not the only kind. Arguments may work with looser connections; the various possibilities fall on a kind of spectrum.

A source for the spectrum theory is Stephen Thomas’ text, Practical Reasoning in Natural Language. Like deductivists, Thomas requires that sound arguments be valid and have true premises. But unlike deductivists, Thomas defines ‘valid’ in a broad sense so that it applies not only to deductively valid arguments. In the first edition of his book, Thomas speaks frankly of degrees of validity. In the second edition, such references are no longer to be found. But Thomas continues his departure from deductivism by defining ‘valid’ in a way much broader than ‘deductively valid’. For him, ‘valid’ serves as a kind of umbrella term which can embrace a whole spectrum of ways in which the premises can be connected to a conclusion. He puts the point this way:

Valid argument: an argument in which the reasons, assuming or supposing that they were true, genuinely would justify believing or expecting the conclusion to be true.²⁶

A later passage gives further clarification and explains why Thomas refrained from using the expression ‘degrees of validity’ in the second edition of his text.

This book differs from previous logic textbooks by recognising that in natural language, different reasons can support their conclusions with different degrees of support. The concept of ‘degree of support’, or ‘degree of strength’, as it will be called also, corresponds to what some philosophers call ‘degree of confirmation’, in the context of the proof or disproof of scientific theories. If, for example, certain assumptions and evidence highly confirm a certain hypothesis or conclusion, then the degree of support of these assumptions is ‘very strong’. The similar phrase ‘degree of validity’ has been recently used in natural logic … for the same purpose. However, some formal deductive logicians … oppose this way of using the term ‘valid’. So to avoid controversy, the more neutral phrase ‘degree of support’ will be used in this textbook to describe the extent to which a given set of reasons makes the truth of a given conclusion likely or probable. We will distinguish five degrees: nil, weak, moderate, strong, and deductively valid.²⁷

The degrees of support may be thought of as lying on a spectrum of looser and tighter connections between the premises and conclusion. At one end of the spectrum we have no support at all; at the other end, we have deductive entailment, regarded as full support. Support is not an all or nothing matter. Whereas deductivists would say that failure to achieve full support constitutes total failure of support — that is to say, no support at all — this will not result from a spectrum theory. Thus, the severely counterintuitive ‘all or nothing’ character of deductivism is avoided. Premises that fail to entail a conclusion may still support it – weakly, moderately, or strongly, according to this view.

Thomas is an appropriate source for the spectrum theory because his is a well-known and widely used text. He really does endorse the theory in the sections of the text quoted here. However, Thomas’ commitment to the spectrum theory is in the final analysis less than whole-hearted because he includes in his text (both editions) a section on missing premises that commits him to deductivism and thereby undercuts his commitment to a spectrum theory.²⁸

Thomas does not consistently maintain his spectrum theory. His initial statement of the spectrum theory locates the deductive connection in a paradigmatic role on the spectrum. It is the strongest, tightest form of support. That role may explain his later desire to supplement arguments with ‘lesser’ connections to the point where they become deductively valid. He works with an uneasy and inconsistent combination of deductivism and a spectrum theory.

Another source for the spectrum theory is Maurice Finocchiaro’s article, ‘Fallacies and the Evaluation of Reasoning’. In that paper, Finocchiaro’s main concern is the interpretation of natural argumentation. He sees a tendency among some informal logicians to rely on insensitive and uncharitable interpretation in order to find fallacies in natural argumentation. In developing this theme, Finocchiaro briefly states a theory of argument:

if a fallacy is defined as a type of common but logically incorrect argument, the various types would have to be the following: (1) arguments claiming to be deductively valid but which are actually invalid; (2) arguments claiming to be inductively strong but which are actually inductively weak; (3) arguments claiming to have some inductive strength but which have none. There is no way for an argument to be a fallacy without falling into one of the three above-mentioned classes.²⁹

We may understand Finocchiaro as maintaining a spectrum theory. He locates fewer divisions on his spectrum than Thomas did on his, but the basic theme is similar: there are different degrees of support. Finocchiaro speaks of the connections ‘claimed’ in an argument, rather than speaking of the connections which actually exist. This phrase poses interpretive problems, since many arguers are not readily interpreted as ‘claiming’ any degree of support. It is merely that, insofar as they are putting forward premises in support of a conclusion, they are claiming support. In other words, we can interpret them as claiming support but not some particular degree of support. Language (at least English) does not have the vocabulary to reliably express claims about degrees of inferential support.

Just as Thomas’ theory was stated with an apparent reliance on deductive connection as the tightest (best?) kind of connection, and is uneasily combined in his text with deductivism, Finocchiaro’s theory has echoes of another concept of reasoning. He seems to have the inductive-deductive dichotomy in his mind, and to superimpose it on a spectrum by seeing ‘weak inductive strength’, ‘strong inductive strength’, and ‘deductive validity’ as three different degrees of the same thing.

Several people with practical experience teaching students to analyze naturally occurring arguments have expressed interest in and sympathy for some kind of spectrum theory. It is unfortunate that there seems to be no detailed statement of such a theory in the philosophical literature. Statements of the theory cited here are brief, and echo aspects of other incompatible theories.

It is not surprising that teachers and students of natural argumentation should find a spectrum theory initially attractive. It strikes a convenient balance between monolithic and pluralistic theories. Like monolithic theories, it avoids the need to classify arguments. Given the flexibility of language and the indeterminacy of arguers’ intentions, this is an attractive aspect of the theory. However, like pluralistic theories, the spectrum theory is able to avoid the need to impose one demanding standard for good inference on all natural arguments. This too is a desirable result, given the immense variety we find in naturally occurring arguments. The spectrum theory is flexible and avoids two undesirable results. It does not imply that most natural arguments are worthless. Nor does it imply that all natural arguments have inferential merit. Fallacies will presumably be those arguments which have no connection (nil, according to Thomas) between premises and conclusion or in which the connection ‘claimed’ is stronger than the connection that exists. Though Finocchiaro in particular is sceptical about the actual existence of fallacies in real argumentation, there is nothing in a spectrum theory as such which implies this result.

4a. What’s on the Spectrum?

The chief flaw with the spectrum theory is that it is too undeveloped to offer real understanding. It appears admirably flexible and easy to apply because of its allowance for various degrees of connection, ranging on a spectrum from no connection at all to a deductively valid entailment. And yet it is no accident that one version of the theory wandered into deductivism and another is stated with strong echoes of the positivistic theory that all arguments are either inductive (as in empirical science) or deductive (as in logic and mathematics). These aspects reflect the lack of theoretical underpinning for the spectrum theory. The problem is that we are given no explanation of what the degrees of support are degrees of. They cannot be degrees of deductive validity, because that notion makes no sense. Deductive validity is all or nothing. An inference from P to Q either is deductively valid or it is not; there is no such thing as making it part way.

If P fails to entail Q, but seems nevertheless to offer some reason for Q (as in ‘the car has a good repair record according to Consumer Reports, so you will not have much problem with repairs if you buy it’), we may say P does support Q, though it does not entail Q. But support in this case is not a weaker version of deductive support. It is not a ‘degree’ of deductive support. Rather, it is something else.

A closely related point is that the nature of the ‘spectrum’ on which the various degrees of support are located has yet to be explained. Consider three arguments which are, on the face of it, non-deductive in type:

1. (Context: A young philosopher contended that the academic institution of tenure was unjust because it worked to deprive young people of opportunities that older people had had. The following was written in reply by a senior professor.)

   But consider this ‘injustice’ as well. My home was purchased only a decade ago, at less than half what it would bring on the market now, and throughout that period interest charges on the mortgage have averaged a single-digit percentage. A much younger person would find it difficult, if not impossible, to purchase a comparable dwelling now. Yet now one would suggest that, because of this, I should give up ownership and compete with homeless individuals for the three or five year leasing of it. Had that ever been a foreseeable eventuality, I would obviously not have ‘bought’ it in the first place. And one can multiply examples of similar ‘injustice‘.³⁰

2. (Context: This brief argument appears in an essay in which the author contends that theology is not an open-minded and reasonable inquiry, and that this fact about theology constitutes the major difference between it and philosophy.)

   ‘That a man’s being an atheist is an absolute bar to his occupying a chair (in theology) proves that theology is not an open-minded and reasonable inquiry.’³¹

3. (Context: This passage is taken from Michael Walzer, Just and Unjust Wars. Walzer is discussing the principle that those who are going to do the actual fighting in a war should have to consent, before going off to fight, to the idea that the war is indeed a just one.)
   
   ‘Napoleon is said to have boasted to Metternich that he could afford to lose 30,000 men a month. Perhaps he could have lost that many and still have maintained political support at home. But he could not have done so, I think, had he had to ask the men he was about to ‘lose’. Soldiers might agree to such losses in a war forced upon them by the enemy, a war of national defence, but not in the sort of wars that Napoleon fought. The need to seek their consent… would surely limit the occasions of war, and if there were any change at all of reciprocity from the other side, it would limit its means too.’³²

Example (A) is an attempt at refutation by logical analogy. The senior philosopher compares the younger philosopher’s claim with a comparable claim about housing or other goods that are purchased at varying times under varying conditions. He maintains that the tenure argument is parallel to an implausible argument that could be given in those contexts and is, therefore, itself implausible. Example (B) is hard to classify. A single point about the institution of chairs in theology is said to ‘prove’ that theology is not an open-minded and reasonable inquiry. This seems to be ‘good reasons’ argument, with only one reason advanced. Example (C) might be called a hypothetical induction. The author envisages a situation regarding Napoleon’s troops and states that these troops would not have consented to heavy losses in a war of conquest. He infers from premises about what would have happened in those circumstances a more general conclusion to the effect that asking soldiers’ consent would limit the occasions of war.

Now let us try to apply a spectrum theory of argument to these examples. If there are degrees of support, and if these degrees are locatable on a kind of logical spectrum as ‘more’ and ‘less’ of something or other, then we should be able to roughly locate these examples. All seem to be cases in which the premises offer ‘some support’ to the conclusion. No doubt it is this appearance of degrees and qualifications of support, as opposed to the all-or-nothing of deductive validity, that makes the spectrum theory initially appealing. The problem is that the spectrum theory tells us nothing about these degrees of support. It does not indicate what kind of support premises might offer, or whether and why (for example) A might be a stronger argument than B. It is not even clear that it makes sense to think of A as having more or less than the same kind of ‘connection’ which either holds or fails to hold in C. The spectrum theory is only a metaphor until it can tell us more about what degrees of support (or connection, between premises and conclusion) are degrees of and what constitutes a greater or lesser degree. Are what appear to be different styles of argument, as exemplified in these cases. When we come to concrete cases, we do not seem to know what to put where on the spectrum and why, or even why there is just one spectrum. The theory is only a metaphor, and unless we are prepared to develop the idea that there are degrees of deductive validity, we cannot turn it into more than that.

5. Better Theories are Needed

We have several nonformal theories of argument, coexisting almost unnoticed with the common philosophical view that the very notion of a nonformal theory of argument is absurd. And yet the notion of a nonformal theory of argument is not absurd. Interesting issues of justification and pedagogy could be illuminated by such a theory. The cultivation of skills in reasoning and critical thinking will surely require, among other things, a sensitivity to the phenomena of natural argument and a good understanding of various types of legitimate and illegitimate inference. Indeed, nonformal theories of argument – especially the three treated here – are very commonly stated and appealed to by philosophers. The problem is that such theories are merely cited. They are not articulated, developed, or defended. More work is clearly needed. A fourth nonformal theory of argument, called here Positivism, is discussed in the next chapter.

This account has emphasized a single problem throughout: inference assessment. Traditional logic virtually restricted itself to that dimension of argument appraisal, so that current theories tend also to emphasize it. But this is not the only aspect of argument analysis open to theoretical scrutiny. We can see this even by looking at themes and issues that arise from the theories considered here. The discipline-specific theory, for instance, tells us how to appraise the premises of arguments. We should locate the argument in a discipline and go to that discipline in order to discover the epistemic standards that will allow us to determine whether its premises are true. The deductivist theory, in its reconstructivist version, depends on a view of the correct way to interpret discourse; this dependence arises from the need for extensive supplementation with premises regarded as missing. Interpretive principles are also presumed by some theories (not considered here), that emphasize arguers’ intentions as a central factor in the classification of arguments. Finocchiaro’s suggestion that we have to see what kind of strength is ‘claimed’ relates to these views. We have seen that common versions of deductivism make the truth of premises a necessary condition for the soundness of arguments. Some theorists have argued that this condition is too demanding and that the acceptability of premises to the audience to whom the argument is addressed is preferable as a condition of premise adequacy.³³ The nature of argument as a social institution for inter-personal persuasion and debate, and the bearing of features of and relations between persons on logical appraisal are further topics that need to be considered.

These issues arise from a preliminary examination of theories of argument primarily occupied with the traditional issue of inference appraisal. Topics in a full-fledged theory of argument will extend beyond the classification of arguments as to type and appraisal of the correctness of the inferences on which they depend and lead to broader issues of epistemology, pragmatics, and ethics.

These further topics fall broadly into two areas. One involves principles and policy having to do with the interpretation of discourse: the identification of arguments; the location of their premises and conclusions; the task of supplying unstated premises or conclusions; charity as a principle of interpretation; and the role of arguer’s intentions and beliefs in proper interpretation. The other has to do with the pragmatics and dialectics of argument: whether premises in a good argument need be true or only acceptable to an audience; whether personal attributes of arguers having to do with their authority or credibility ever have a legitimate bearing on their appraisal of the argument; how rebuttals, pros and cons, and counter-arguments are to fit within our structural models; and many related topics. The role of such factors in a theory of argument is already tacitly acknowledged in logical tradition because they bear upon our understanding of the traditional fallacies of begging the question, ad hominem, straw man, and appealing to authority.

Doubtless other theories of argument could be stated. The widely held belief that there are two basic kinds of argument, deductive and inductive, merits treatment on its own. The theories discussed here were chosen either because of their apparent wide appeal to philosophers in general or because of their appeal to persons interested in informal logic. These theories are not satisfactory: we await a better one.

Notes

1. John E. McPeck, Critical Thinking and Education, (Oxford: Martin Robertson, 1981), pp. 70- 71.

2. For more discussion on different senses of ‘formal’, see subsequent essays: ‘Four Reasons There are no Fallacies?’ and ‘Formalism and Informalism in Theories of Reasoning and Argument.’

3. Cf. Trudy Govier, ‘Review of Critical Thinking and Education’, Dialogue 22 (1983), pp. 170-175. At the Second International Symposium on Informal Logic, held in Windsor in June, 1983, McPeck agreed that his account depended on a conflation of the general and the formal.

4. I have defended a principle close to this one in ‘Ad Hominem: Revising the Textbooks’, (Teaching Philosophy, 6 (1983), pp. 13-24).

5. McPeck, Critical Thinking and Education, page 13.

6. Ibid., p. 72.

7. Ibid., p. 81.

8. See S. Toulmin, R. Rieke, and A. Janik, An Introduction to Reasoning (New York: Macmillan, 1979) and S.F. Toulmin, The Uses of Argument (Cambridge Eng.: Cambridge University Press, 1958.) Despite his fame as the originator of a field dependent or discipline-specific theory of argument, there is a clear sense in which Toulmin does not hold such a theory.

9. Ralph H. Johnson, ‘Toulmin’s Bold Experiment’, Parts One and Two (Informal Logic Newsletter, iii, nos. 2 and 3 (March and June, 1981). Quoted passage is in Part One, p. 24.

10. F. H. van Eemeren, R. Grootendorst, and T. Kruiger, The Study of Argumentation (New York: Irvington Publishers, 1984), pp. 203-204.

11. See my review in Dialogue, 1983; also Richard Paul’s review in Informal Logic vi (1984); and Perry Weddle’s review in C. T. (newsletter from the Critical Thinking Project at California State University, Sacramento), Vol. I, no. 2.

12. It is relatively uncontroversial. It may be controversial that some one discipline will supply the information necessary to evaluate a premise. It is not controversial that we should typically need to look outside logic (formal or informal) in order to assess the premises of arguments.

13. Weddle, Review of McPeck, cited above, p. 4.

14. D. Stove, ‘Deductivism’, Australasian Journal of Philosophy, Vol. 48, no. I (May, 1970), pp.76-98.

15. K. Lambert and W. Ulrich, The Nature of Argument, (New York: Macmillan, 1980), p.18.

16. Ibid., pp. 19-20. ‘As we shall shortly see, logical validity and logical invalidity are features of argument that depend only upon their logical form.’ (page 10) I discuss this aspect of Lambert and Ulrich’s account in ‘Four Reasons There are no Fallacies?’.

17. This view has been argued by J.A. Blair in an unpublished paper on the importance of context in argument analysis. It is endorsed in R.H. Johnson and J.A. Blair’s Logical Self-Defence (Toronto: McGraw-Hill-Ryerson, 1983), and in my own text, A Practical Study of Argument First edition (Belmont, Calif.: Wadsworth, 1985).

18. Gerald M. Nosich, Reasons and Arguments, (Belmont, Calif.: Wadsworth, 1982), p. 27.

19. Carl Wellman, Challenge and Response: Justification in Ethics, (Carbondale, Ill.: Southern Illinois University Press, 1971).

20. Stove, ‘Deductivism’, pp. 76-77.

21. Notably that of S. N. Thomas. See the discussion below for documentation and further comments. See also my discussion of the deductivist policy on missing premises in ‘The Problem of Missing Premises’.

22. Compare Lewis Carroll, ‘What Achilles Said to the Tortoise’ reprinted in Douglas Hofstadter, Godel, Escher, Bach (New York: Basic Books, 1979).

23. I argue this point at length in the chapter on missing premises.

24. The assumption here is not that tradition must be right. Rather, there are two more subtle appeals. First, tradition should not be presumed to be wrong without better reason than an ad hoc theory of missing premises devised to protect deductivist assumptions.. Second, most deductivists do want to preserve their belief in fallacies, especially formal fallacies.

25. A fallacy is supposed to be a mistake in reasoning. A false or unacceptable premise might be said to constitute a fallacy in the broader, more colloquial sense in which any false belief is sometimes said to be fallacious. However, it has long been recognized that this broad sense of ‘fallacy’ is distinct from the stricter logical sense. A standard definition of the latter is that of S.F. Barker, who says in Elements of Logic (New York: McGraw-Hill, 1980; Third Edition) that ‘a fallacy is a logical mistake in reasoning. When there are premises and a conclusion that, through some logical error, is mistakenly thought to be proved by them, then and only then is there a fallacy in the logical sense.’ The use of ‘deceptive’ in my own statement should not be taken to imply that arguers who employ fallacies always do so with an intention to deceive their audience. Fallacies can be used in the sincere belief that they are good arguments. Rather, the point is that fallacies are deceptive in the sense that they tend to strike people who read or hear them as good arguments. Compare ‘Four Reasons There are no Fallacies?’.

26. S. N. Thomas, Practical Reasoning in Natural Language, (Englewood Cliffs, N.J.: Prentice Hall, Second Edition, 1981), pp. 96 -97.

27. Ibid., pp. 98-99.

28. This aspect of Thomas’s text is discussed again in the

chapter on missing premises.

29. Maurice Finocchiaro, ‘Fallacies and the Evaluation of Reasoning’, (American Philosophical Quarterly, 1981), page 15. Finocchiaro has confirmed in conversation that he wished to express a spectrum theory in this passage.

30. R. Puccetti in the Canadian Association of University Teachers Bulletin for March, 1976.

31. From J. Robinson, ‘Reason and Faith’, in Burr and Goldinger, Editors, Philosophy and Contemporary Issues,  (London: Macmillan, 1976).

32. Michael Walzer, Just and Unjust Wars (New York: Basic Books, 1977), p. 29.

33. J. Anthony Blair has argued this point and the sort of view he advocates has been incorporated in several texts, as noted above in footnote 17.