8 Reasons Why Arguments and Explanations are Different

Broadly speaking, the current consensus about the basic distinction is similar to that theme of this chapter. Argument and explanation are different; generally they differ pragmatically. Reasoning is used in both, and the same indicator words are used in both.

This chapter represents my response to a challenge issued by S.N. Thomas, who maintained on the basis of a number of tricky cases that the argument/explanation distinction did not hold up to scrutiny. Looking back at the chapter many years later, I still find myself impressed by the examples he put forward. I would agree now, as I did then, that the distinction between argument and explanation is not an exclusive one. It’s quite possible for the same set of statements to provide both an argument that a conclusion C is true and an explanation as to why it is (or how it came to be) that C should be true. Yet it is still the case that argument and explanation differ from a pragmatic point of view. The ‘why?’ of explanation differs from the ‘why?’ of argument. Explaining, one will offer an account (usually causal) as to why or how C came to be true. Arguing, one will cite reasons or evidence purporting to show that C is true. Explaining, one presumes general agreement about C; arguing one presumes the actuality or possibility of disagreement about C. Thomas maintained that the argument/explanation distinction should be dispensed with because it could not be drawn clearly and admitted too many borderline cases. Still more significantly, he found cases that qualified both as argument and as explanation and thus undermined the dichotomy. Working through some of his challenging examples, I agreed that a passage could constitute both argument and explanation but resisted renouncing the distinction altogether on that account. In other words, I preserved the binary but allowed that it was not exclusive.

In a 2010 article, ”Argument Explanation Complementarity and the Structure of Informal Reasoning” Gregory Randolph Mayes similarly maintained a distinction between argument and explanation. Mayes put it this way: in an argument, the conclusion is disputed; in an explanation, the conclusion (or statement that would stand in the place occupied by the conclusion) is already accepted. One can ask just who it is that is referred to as accepting or disputing claim C. Mayes maintains that it is the arguer. The arguer can of course get the matter wrong. For example she might suppose that the persons she is addressing grant that C and offer to them an explanation of C. If she is mistaken about that, the explanation will not be appropriate. The audience could be lured into supposing that C is true, or it could expect an argument and be disappointed that what the arguer has to offer will not provide justifying evidence or reasons. Mayes is aware of such issues; nevertheless he sustains his view that the arguer’s states of acceptance or doubt determine the argument or explanation status of her discourse.

Mayes offers lucid and interesting examples of how argument and explanation may be combined in discourse. For instance, one might cite a claim to support a conclusion (argument) and then offer an account of how that claim came to be true (explanation). As he says, argument and explanation can be complementary to each other in these sorts of cases.

A 2017 article “Argument or Explanation: Who is to Decide?” appeared just as I was about to write this introduction. The author, Michel Dufour, points out that neither Thomas nor myself questioned the exhaustiveness of the argument/explanation binary. (I had noted a third alternative — descriptive discourse that is neither justificatory nor explanatory – in my textbook.) Dufour maintained that one does not always find disagreement about the conclusion of an argument. I had actually acknowledged that one can look for an argument that would justify a claim C even when one accepts C, as for example in a context of inquiry. Dufour states that it is unclear who is to decide whether a claim C is ‘certain’ enough to be explained instead of argued for, and rejects the idea that the arguer himself or herself should hold authority of that matter. Perhaps claim C is something that people neither agree nor disagree about. Perhaps they have barely considered the matter, or do not care enough about it to bother. Then the pragmatic distinctions will not take hold. In this case, the binary is not exhaustive. Is the discourse an argument or an explanation? The answer should be neither.

Philosophers have commonly distinguished between arguments and explanations. In arguments, premises are stated in an attempt to prove, or justify, a conclusion. In explanations, statements are made in an attempt to account for, or show the cause of, a state of affairs. Most introductory accounts of argument take this contrast for granted. Nevertheless, there are a number of interesting and relatively unexplored issues about the relation, similarities, and distinction between argument and explanation.

The so-called logical indicator words – ‘thus’, ‘therefore’, ‘since’, ‘because’, ‘so’, and many others, are as common in explanations as they are in arguments. Those which precede the conclusions in arguments may equally well precede what is explained in an explanation. Here is an example:

When censorship boards conduct their deliberations in secret, public accountability is lost. Public accountability is essential. Thus, such proceedings should be recorded and public access to the records should be allowed.

In this example, ‘thus’ is used in its paradigmatic logical role, preceding the conclusion in an argument. But in other cases, ‘thus’ functions just as naturally in an explanation, as in:

She ate about the same amount as usual but got much more exercise, running after the children and doing all the housework and gardening. Thus she lost a lot of weight over the summer.

Here the fact explained is preceded by ‘thus.’l Similarly, words like ‘because’, ‘since’, and ‘for’, which are used to introduce premises in arguments, are also often used to introduce explaining statements in explanations.

According to the classic deductive-nomological account, explanation is one type of argument.2 Although this account is now widely criticized, it was dominant in the philosophy of science for several decades and still enjoys influence. Within influential circles in the philosophy of science, the notion of argument has been more or less taken for granted, with arguments being understood as paradigmatically deductive. An especially clear and intellectually important type is the subsuming deduction: ‘All As are Bs; this is an A; therefore this is a B’. In the influential covering law model of scientific explanation, scientific explanations are seen as having this form (at least implicitly), so that every complete scientific explanation is at the same time a deductively valid argument. The relation between argument and scientific explanation has been studied largely in the context of the issue of whether scientific explanations can or should be made to fit this standard pattern or a statistical variation of it. (Most A’s are B’s; this is an A; therefore this is most likely a B.) Although other types of arguments, such as analogies and conductive arguments, might have been explored for their potential as models for other types of scientific explanation, they were not. Nor does there seem to have been any attempt to explore more sophisticated cumulative argument structures as models for elaborate explanations.3

This influential discussion of the relation between explanation and argument appears impoverished if examined from the perspective of a richer and more sensitive theory of argument. Not all arguments are deductive unless one adopts a sweeping missing premise policy that requires supplementing stated premises so as to make them deductively entail the conclusion. Furthermore, scientific explanations are not the only explanations. The philosophical studies of scientific explanation and its relation to argument could profitably be broadened by greater reference to explanation outside science as well as to nondeductive and cumulative patterns of argument.

The fact remains, however, that many serious and prominent thinkers retain the view that scientific explanations constitute a type of deductively valid argument. The enduring influence of this model provides one incentive to reexamine that textbook contrast between argument and explanation.

Another incentive arises from pedagogical experience. Instructors often find it difficult to teach students the distinction between explanation and argument. Students find the distinction hard to grasp in theory and difficult to apply in practice. In a culture that does not emphasize the importance of providing supporting reasons for one’s claims, questions as to ‘why?’ are often taken as requesting explanations for how people have come to think as they do. Issues of justifiability may disappear. Such crucial terms as ‘why’, ‘reasons’, and ‘because’ fit naturally into both explanations and arguments. People may become unaccustomed to rational argument and find it hard to appreciate any contrast between requests to explain why one thinks as one does and requests, on the other hand, to provide rational support for one’s claims.

Even when the distinction between explanation and argument is grasped in theory, many passages, real or invented, can be interpreted as either explanation or argument. To illustrate this problem, consider the following example, cited by S.N. Thomas:

Managers who at an early stage showed much promise, career growth, and mobility may find themselves classified as nonpromotable for any of a dozen reasons … Once labeled nonpromotable, a person is frequently put on a shelf and only tolerated within an organization. There, there is a great potential for the development of insecurity and fear in a manager in an organization, since he has few legal rights for his protection and must develop himself so that the organization continually views him as a valuable asset.

Thomas remarks of this passage:

Here both explanation and justification seem to be going on. The authors justify their statement that there is great potential for the development of insecurity and fear in a manager in an organization by explaining how and why this potential exists (a manager ‘has few legal rights’, he may be ‘classified as nonpromotable‘ and ‘put on a shelf, etc.) The authors justify their statement that this situation exists by showing the facts that lead to, or cause, its existence.

In fact, Thomas finds such passages so prevalent that he rejects the distinction between argument and explanation in his popular text.4 He sees himself as teaching students to identify, understand, and evaluate reasoning which, he says, appears both in ‘justifications’ (his word for what standard theory calls arguments) and in explanations. Given the existence of borderline cases, and given that reasoning occurs both in explanations and in ‘justifications’, Thomas makes the unorthodox decision to use the word ‘argument’ broadly enough to cover explanatory reasoning as well as justificatory reasoning.

Most theorists seek to preserve a distinction between argument and explanation, even in the face of such difficulties. One common approach brings in the relative uncertainty of the conclusion of an argument compared to its premises, and contrasts this with the relative certainty of the explained fact (explanandum) in an explanation, as contrasted with that of the explaining facts (explanans). In an argument, we typically try to justify a conclusion that is, in the context, in doubt. We state premises that we regard as more certain than the conclusion and capable of giving that conclusion rational support. We reason from the premises to the conclusion, and offer those premises to an audience on the supposition that they can support the conclusion – show that it is true, or acceptable. The pragmatic direction in argument, then, is from premises to conclusion.

Typically, premises are taken as given, or at least as more acceptable than the conclusion at the outset of the reasoning. The point of arguing is to rationally persuade an audience on the basis of these premises that the conclusion is true or plausible. The pragmatics of explanation are quite different. We do not usually try to explain something unless we take it to be a phenomenon or fact. (There is no need to explain there being 80% of males among human births in Canada in 1984, for this was not a phenomenon.) To offer an explanation for some phenomenon is generally to presume that it is a genuine phenomenon. If it is not, there is nothing to explain. We do reason in explaining: we reason from presumed phenomena or regularities to the fact we are trying to explain. (‘It is because of <explanans> that <explanandum>.’)5 If these explaining factors hold, then the fact we are seeking to explain would be understandable; it would ‘make sense’. Sometimes the explaining statements are as well-known as the fact that is to be explained, but sometimes they are not. In such cases, we may even employ our explanation in an abductive argument (inference-to-the-best-explanation).

Regarding argument and explanation, the central point is the contrast in pragmatic direction. In an explanation, the explained statement is as well-known as the explaining statements, perhaps better known. In an argument the premises cited as justification are typically better known than the conclusion. Thus the relevant beliefs of arguers and explainers and their respective audiences differ significantly. The ‘certainty shift’ often is different: in an argument certainty moves from the premises to the conclusion, whereas in an explanation it either does not shift or shifts from the fact to be explained to the explanatory hypothesis.

In Philosophical Explanations, Robert Nozick puts the contrast this way:6

A proof transmits conviction from its premises down to its conclusion, so it must start with premises (q) for which there is already conviction; otherwise, there will be nothing to transmit. An explanation, on the other hand, may introduce explanatory hypotheses (q) which are not already believed, from which to deduce p in explanatory fashion. Success in this explanatory deduction may lend support and induce belief, previously absent, in the hypothesis.

Nozick’s preliminary version of the distinction between argument and explanation seems essentially correct, but the full story is more complicated. Things are unfortunately rather messier than Nozick’s account suggests. It is not a necessary condition of the occurrence of argument that the conclusion be in doubt. We may argue for conclusions that we already believe, for example in contexts where we accept a claim but seek a convincing justification for it. Nor is it strictly a necessary condition of explanation that the explanandum be granted as a fact. Occasionally, explanations are offered for potentially true statements. (‘If such and such were the case, it could be because of so and so.’) Transcendental arguments combine argument and explanation, in that a conclusion derived from a point about experience or consciousness is supposed to explain the very phenomena that prove its necessity.7 Some arguments set out proofs in such order and detail that they not only demonstrate that a conclusion is true, but at the same time serve to explain why it is true. On Nozick’s account, this should be logically impossible, as the demands on relative knowledge levels would be contradictory.8 Nozick’s pragmatic account, while plausible, stands in need of qualification and development.

1. Looking at Thomas’ Challenge

In the Instructor’s Manual for the second edition of his text, S.N. Thomas includes an interesting short essay defending and explaining his unorthodox pedagogical policy of abandoning the distinction between arguments and explanations. Thomas offers four basic reasons for his position.

  1. It is impossible to include all justificatory discourses within the scope of logic while excluding all explanatory discourses. This is because many pieces of reasoning can defensibly be classified ‘as being both ‘justificatory’ and ‘explanatory’.’ In fact, Thomas states, ‘Many reasoned discourses in natural language are ‘justificatory’ and’ explanatory’ at the same time and on the same interpretation.9 Thomas is not merely stating that many passages are hard to classify in that they could either be seen as justificatory or as explanatory. Rather, his point is that many reasoned passages can correctly be seen as both justificatory and explanatory, where this duality is not a result of semantic or structural ambiguities. An argument that X is true may also constitute an explanation why X is true. Thomas speaks of what is included and excluded from the scope of logic because logic has traditionally regarded argument as its primary territory. However, one might agree that logic should include the task of evaluating the reasoning used in explanations and nevertheless wish to preserve the distinction between explanation and argument.

  2. The distinction between justification and explanation needs to be based on extra-logical features of discourses such as function, social purpose, normal contexts, and beliefs of speakers and writers. Such beliefs may vary from person to person and from situation to situation. If explanatory discourses are to be excluded from the scope of logic, their exclusion would depend on extra-logical and variable factors. ‘This dependency would be undesirable because the scope of logic should not fluctuate with extra-logical individual psychological variables. This is a reason both against trying to restrict the scope of logic to ‘justifications’ and against trying to exclude some explanations on the grounds that they are ‘nonjustificatory.10

  3. Explanations and justifications both employ reasoning, and, Thomas says, ‘in both cases, a similar relationship should exist between the components of the reasoning.’11 Since it is the task of logic to appraise reasoning, logic should thus deal with both types of discourse. In the classic hypothetico-deductive model of scientific explanation, explanations are regarded as arguments. Viewed in this way, explanations can be evaluated by ‘the same logical criteria (of validity and soundness) as justificatory discourse’.

  4. It is better pedagogically to require students to distinguish reasoning from nonreasoning than to require them to distinguish argument from nonjustificatory explanation. This is because the relevant pragmatic factors are often not revealed in the passages cited in textbooks and because borderline cases are so common. As a result, the boundary of the set of reasoned discourses (i.e. the boundary of the class of reasoned discourses including both justifications and explanations) appears to be not only more relevant to logic, but is also much clearer than is the broad blurry boundary between justificatory and nonjustificatory reasoning.’12

We can see a number of distinct themes in Thomas’s challenging account. His idea that logic should encompass the appraisal of the reasoning used in explanations can be accepted without renouncing the distinction between explanation and argument. The claim that many natural discourses are difficult to classify as either justificatory or explanatory, especially when taken out of context, is also quite acceptable and may be pedagogically important, though it does not entail that the distinction between explanation and argument should be relinquished altogether. To say that pragmatic factors are required to apply the distinction is quite consistent with the sort of account Nozick offers.

The central and most revisionary claims in Thomas’s account reduce to two. First, the very same statements, on the same interpretation, can constitute both an argument and an explanation. Second, the very same logical criteria apply both to explanations and to arguments. If these claims were true, then any distinction between argument and explanation would indeed be relatively unimportant within logic, both pedagogically and theoretically.

2. Arguments that are not Explanations and Explanations that are not Arguments

No one has seriously claimed that all arguments are explanations, though some have claimed that all explanations are arguments. For the sake of completeness, however, let us see why not all arguments are explanations. Consider the following example:

  1.  Jones is a Liberal.

  2.  Jones is fat.

  3.  Jones is a bachelor.

  4. therefore,

  5.  Jones is a fat Liberal bachelor.

  6. There are fat Liberal bachelors.

Here (5) is conclusively proven, given the premises. But the phenomenon described in (5) is not explained.

In this argument, the conclusion generalizes on separate particular facts, and these facts are not adequate to explain why it should be true. To explain something is to account for it, to show how or why it came to be and why it is as it is. Typically, explanations set a phenomenon in a broader context, either subsuming it under a law, indicating one or more of its causes, showing how it fits a pattern how it is similar to a case which is already well understood (analogy), or how it is somehow to be expected given other factors that are understood. Many arguments do not do this, even though they provide evidence or reasons to show a statement true or plausible. For this reason, examples like the one just cited are easy to generate. Statements can prove, or provide good evidence for a conclusion, C, without explaining why C is true.

These are good arguments even by strict standards. The example above doubtless has true premises, and it is deductively valid. If interpreted as an explanation, this discourse would constitute a very poor one. Thomas’s claim that arguments and explanations can be assessed by the same logical criteria can be seen to be false. There are many uncontroversially good arguments that are not explanations and that would be poor explanations were they taken as explanatory.

Wesley Salmon presents a relevant case in a paper in which he argues that explanations are not arguments. He supposes that we have good inductive evidence that doctors are experts at predicting which children will catch the measles.13 Given this, we might argue some such thing as:

  1.  Doctor Smith has predicted that Susan will catch the measles.

  2.  Doctors are almost always correct when they predict that children will catch the measles.
    Therefore, probably,

  3.  Susan will catch the measles.

Here we have a good inductive argument for (3), but we have no explanation of (3). It is not established that Susan will get the measles, although this is a reasonable thing to believe. Even if we wanted to explain why Susan will probably get the measles, the expertise of doctors would not be the right sort of factor to refer to – exposure to others, or failure to get vaccinated would. Surely Susan would not get the measles as the result of a doctor’s prediction! The prediction is not a cause. Yet we have a good inductive argument for the claim that Susan will get the measles.

A comparable point can be made about retroactive inductive arguments. For instance, consider an argument from the presence of fossilized sea shells in Alberta today (S) to the claim that there was once an immense sea covering Alberta (C). S, conjoined with information about the fossils, provides inductive evidence for C. Retrodictively, we may infer C from present facts. S can give evidence for C in a retrodictive context just as a comparable claim might provide evidence in a predictive context. Nevertheless, S cannot in such a context explain C. The point is especially obvious in a retroactive argument, since the temporal relations would not work for explanation.14 The presence of sea shells in Alberta in the present cannot possibly account for there having been a sea there millions of years ago.

Similar points can be made about many inductive arguments. The evidence cited may provide a good basis for belief in the conclusion without explaining that conclusion. Consider, as another example, an inductive analogy citing effects on rats as a basis for a predicted effect on humans. The evidence about rats could not in principle explain such an effect on humans.

Reflecting in a mathematical context, Philip Kitcher endorsed the distinction between argument and explanation, saying:

there are cases in which we have a rigorous argument from known premises, but in which we do not understand why the conclusion is true.15

In such cases, we have argument and no explanation. And there are many such examples. Thus many perfectly good arguments have no prospects as explanations.

Thomas’s claim that the same criteria can be used to appraise both arguments and explanations cannot be correct. We need a distinction between argument and explanation, and we need different criteria of appraisal for each.

Perhaps further conditions are needed for explanation. Or perhaps the conditions of epistemic and logical appraisal are quite distinct. Some examples make it seem as though explanation demands more than argument. It might be that good explanation demands good argument for the explanandum and more besides. This is the assumption behind deductive nomological accounts in which explanation is regarded as a special type of argument. However, for this thesis too, there are problems. The idea that explanation demands more than argument is falsified by the fact that some potentially adequate explanations are utter non-starters as arguments. Consider the following, for instance:

  1.  Smith is a communist sympathizer.

  2.  Cuba is a communist state.

  3.  Smith’s account of conditions in Cuba is flawed and biased.

If taken as premises offering support for (3), (1) and (2) would do a poor job. If we were to appraise this reasoning as an argument we would give it poor marks, because we would expect (1) and (2) to give good evidence in support of (3) and they do not. As an argument, this discourse is ad hominem and extremely weak. However, regarding the discourse as an explanation gives a different result. Doing that, we regard (3) as a claim granted in advance. If it is known or agreed that Smith’s account is biased and we are trying to explain why it is biased, the fact that he is a communist sympathizer offering an account of a communist country could provide the explanation.

Thomas follows logical tradition in regarding the ad hominem as a fallacy. But that view is not consistent with his claim that the same appraisal standards apply both to arguments and explanations, as this example reveals. In this sort of case, the pragmatic difference regarding relative knowledge of the ‘conclusion’ or explanandum is highly significant.

Wesley Salmon provides another kind of example.17 We sometimes explain an event by citing a statistical law according to which that event has a low probability. For instance, the probability that someone exposed to a particular dose of radiation gets leukemia may be less than 5%. Yet if he does get leukemia some years after the exposure, his exposure will be the explanation. A similar example, first cited by Michael Scriven, is that of the syphilis sufferer who gets paresis. Few syphilis sufferers get paresis, but for those who do, their being syphilis sufferers is the explanation. In such cases, an argument from the statistical law to the occurrence of the event will be weak, for the event has a low probability of occurring, given the statistical regularity. Yet the regularity specifies the relationship that (by current scientific standards) explains the event. (Admittedly, that explanation does seem weak and incomplete.) We can explain the phenomenon, knowing that it occurred. If we did not already know that it had occurred, we could not argue that it would occur by citing such a regularity.

No account of reasoning and discourse which dispenses with the distinction between argument and explanation is going to be plausible, because there are many arguments that are not explanations and there are many explanations that are not arguments. Furthermore, an examination of cases indicates that different criteria of appraisal must be at work. There are good arguments that would be non-starters as explanations, and good explanations that would be non-starters as arguments.

3. Why Arguments are not Explanations

That some arguments are not explanations and some explanations are not arguments is to be expected, given the basic pragmatic asymmetry between argument and explanation. The purpose of argument is rational persuasion. A person puts forward an argument in an attempt to persuade an audience that a claim is true on the basis of reasons or evidence that he or she provides in support of the claim. The claim is taken as not accepted in advance of the argument’s being stated, and as rendered acceptable in virtue of the fact that it is adequately supported by the asserted premises. In an argument, an attempt is made to justify, or render rationally acceptable, a conclusion on the basis of proffered premises. Since justifying evidence or reasons may in many cases not be of the appropriate type to explain the phenomena cited in the conclusion – as in a number of the examples cited above – there are many arguments that are not explanations.

In an explanation, an attempt is made to show how or why something came to be as it is. Since explaining a phenomenon presupposes that it occurred, explanatory factors are often not of an appropriate type to provide evidence that it did occur. The underlying pragmatics of argument and explanation make the existence of examples of arguments that are not explanations and explanations that are not arguments entirely intelligible. Pragmatic differences explain the distinction.

It is true that we sometimes argue for conclusions that are not in doubt – as when philosophers construct arguments for the existence of external objects. Argument may be used here as an exploratory device – an instrument of inquiry, as several recent authors have put it. This fact does not undermine the fundamental pragmatic contrast, though.18 Such arguments may be understood as attempts to show how doubts could be resolved were they to occur, and can thus regarded as justificatory. The idea that the premises should be better known than the conclusion is thus preserved. For example, an argument for the existence of external objects, based on premises presuming the existence of other minds, would be considered deficient because this condition would not be met. The premises would not be ‘better known’ or ‘more certain’ than the conclusion. Although standardly we doubt neither other minds nor external objects, in any case where we were ready to put the latter in question, the former would likely be in question as well.

Similarly, the fact that we occasionally consider explanations for phenomena that did not occur can also be understood within the context of the basic asymmetry. Such explanations are accounts of ‘how it could be that X’, based on the tentative supposition that X is the case. How could it be that female criminality would approach the level of male criminality in North America in the 1980s? This isn’t the case, but we might suppose that it is, and see what explanatory factors could be offered in that event – greater participation of women in the labor force, greater responsibility of women for economic dependents, television shows featuring women in forceful and violent roles, and so on. This kind of mental exercise could sometimes be important. It is unusual, but possible, and does not undermine the basic pragmatic asymmetry between argument and explanation.

3a. Kant and Transcendental Arguments

Nor does the intermingling of explanation and argument in transcendental arguments undercut this fundamental distinction. In a transcendental argument, a conclusion C is justified on the grounds that it is a necessary condition for the truth of some premises, K, which are taken as true. These premises describe human knowledge, conceptual structures, or belief systems. The conclusion is deduced from the premises. The explanatory element comes in by reversing the order. It is not that ‘K therefore C’ is both an argument and an explanation. Rather, ‘K therefore C’ is an argument, and ‘C, thus K’ is an explanation, or partial explanation.

Kant, the locus classicus here, says that in such arguments a principle is justified because only given that principle is our knowledge possible. The word ‘only’ refers to the necessary condition relationship on which the justification is based. The idea of making possible introduces explanation. In a transcendental argument, one tries to justify a principle by showing that its truth is a necessary condition of knowledge that we have; therefore, it is true. (Example: in Kant’s account, we have knowledge of geometry and only with an a priori intuition of space could we have that knowledge. Therefore there is an a priori intuition of space.) But the principle that is justified as a necessary condition is also supposed to explain the existence of that knowledge of which it is the condition. The principles describe a feature that helps make that knowledge possible. It is thus part of the explanation as to how we got that knowledge. The knowledge is assumed both in the justification of the principle and in the accompanying explanation. (Again, referring to Kant’s account, we are able to have a priori knowledge in geometry because space is a priori and is ‘in us’.) Granting that we have the knowledge, we argue that the principle is true. Given the truth of the principle, we use it to explain the existence of the knowledge.19 Justification and explanation are both supposed to occur in transcendental arguments, and the compact phrase ‘only given P is K possible’ welds them together. It is crucial to note here that what justifies is not the same as what explains. The existence of transcendental arguments does not undercut the distinction between argument and explanation. Rather, a proper understanding of those arguments presupposes this contrast.

3b. Inference to the Best Explanation

Nor does the existence of arguments that proceed by inference to the best explanation blur the distinction between argument and explanation. Suppose that F is a fact, and that E is proposed as the best explanation for F. We may then argue from F to E, as:

  1.  F

  2.  E is the best explanation for F.
    Therefore, probably,

  3.  E

Such a line of reasoning is an argument; in the argument we try to justify (3). We argue in favour of a hypothesis or theory (E) on the grounds that it would serve as the best explanation of a fact or presumed fact (F). The argument is not at the same time an explanation, nor could it be. What is explained, as the basis for this argument, is F. F appears here as a premise. Those who read arguments as explanations read the conclusion as the explanandum. But here the conclusion would be the explanans. As Nozick remarked, the inference to the best explanation (abductive) arguments presuppose the underlying pragmatic asymmetry between argument and explanation. Only because the explanandum is, in this case, known prior to the explanans are we able to infer the latter from the former. In an argument, the conclusion is not better known than the premises and we (certainly) do not infer the premises from the conclusion.

4. Counterexamples

There remains Thomas’ claim that some discourses constitute both argument and explanation, on the same interpretation.20 Thomas offers several persuasive examples in defense of this controversial thesis. Here are some of his most persuasive cases.

  1. ‘All natural disasters are comforting because they reaffirm our impotence, in which, otherwise, we might stop believing. At times it is strangely sedative to know the extent of your own powerlessness.’ (From Erica Jong, Fear of Flying (New York: New American Library, 1974), p. 204.

  2. ‘Many of the problems of philosophy are of such broad relevance to human concerns, and so complex in their ramifications that they are, in one form or another, perennially present. Though in the course of time they yield in part to philosophical inquiry, they may need to be rethought by each age in the light of its broader scientific knowledge and deepened ethical and religious experience. Better solutions are found by more refined and rigorous methods. Thus, one who approaches the study of philosophy in the hope of understanding the best of what it affords will look for both fundamental issues and contemporary achievements.(From Elizabeth and Monroe Beardsley, ‘Introduction to the Prentice Hall Foundations in Philosophy Series’.)

  3. Man hating is a defense, a refusal, and an affirmation. It is a defense against fear, against pain. It is a refusal to suppress the evidence of one’s experience. It is an affirmation of the cathartic effects of justifiable anger. What is primary is the possibility for release gained from acknowledging its existence, and the renewal that can sometimes accompany its expression. For if I say today, ‘I hate you’, it is in order that tomorrow it might perhaps be easier to say, ‘I love you. (From Ingrid Bengis, Combat in the Erogenous Zone (New York: Alfred A. Knopf, 1972), p. 5.)

  4. Cable television today is at a stage where the general exercise of choice is still possible. If for no better reason than that there is a history of government regulation in the field of television, it remains possible by government action to prohibit it, to permit it, or to promote it almost by fiat. Citizens may still take a hand in shaping cable television’s growth and institutions in a fashion that will bend it to society’s will and society’s best intentions. It is not as yet encumbered by massive vested interests, although that day may be no longer remote. It is not as yet so fixed a part of the national scene, as for example conventional television is, that it appears almost quixotic to re-direct its energies. There is, in short, still time. (From On the Cable: The Report of the Sloan Commission on Cable Communications (New York: McGraw-Hill, 1971), p. 3.)

Example (A) could be either an argument or an explanation. Because the ‘conclusion’ that all natural disasters are comforting is a claim few would assent to, it might seem most plausible to take the passage as an argument. However, (A) is not very convincing either as argument or as explanation. It cannot serve as a good explanation, because there is nothing to be explained unless we are antecedently convinced that natural disasters are comforting. (Unlikely.) Nor do the other statements have sufficient independent plausibility to serve as the premises of an argument that natural disasters are comforting. The passage makes little sense either as an explanation or as an argument. And yet the word ‘because’ seems to require us to interpret it as one or the other or both. The example serves to illustrate Thomas’ point, but its epistemic weakness makes it unconvincing as a test case.

Example (B) occurs in a context that is significant so far as the pragmatic distinction between argument and explanation is concerned. It appears in the introduction to an elementary series in philosophy. The intended audience, then, is students who do not know very much about philosophy. The authors wrote to tell students what to expect from studies of the subject. To take the passage as an explanation is to presume that the students already know or believe that those looking for the best in philosophy will look at both fundamental issues and historical achievements. Pragmatically, this interpretation seems implausible. It makes more sense to regard the passage as an argument. The authors, who have the authority of established philosophers writing an introduction to a series of texts, make statements about the time-significant aspects of philosophical problems; the intention would be that students would accept their premises because of their authority in the context. The conclusion follows from these; it is almost a summary of what has been said before.

Example (C) really contains two sets of reasoning. There is first the reasoning to show that ‘man hating is a defense, a refusal, and an affirmation’. Here, the form is essentially ‘P; Q; R; therefore P and Q and R’. This part of the passage should clearly be taken as an argument. It has no plausibility whatever as an explanation. The supporting statements are particular facts that are summarized in the conclusion. The next part of the passage is harder to interpret: What is primary is the possibility for release gained from acknowledging its (the hatred’s) existence, and the renewal that can sometimes accompany its expression. For if I say today ‘I hate you’, it is in order that tomorrow it might perhaps be easier to say, ‘I love you‘.’ This passage is similar to the one from Fear of Flying (A). Its epistemic credentials are feeble, whether we regard it as explanation, argument, neither, or both. Were it not for the word ‘for’ at the beginning of the second sentence, there would be little basis for seeing it as reasoned at all. (In fact, what we see as reasoning, assuming ‘for’ to mean ‘because’, is so weak that there may be a charitable inclination to search for another function for the word ‘for’ in this context. Perhaps it is serving merely as conjunction.) Given the presence of this word, the sentences make equal sense as explanation or argument; the second may be regarded either as the explanation for the first, its truth being granted, or as a reason (premise) for believing that the first is true. Given the controversial and rather surprising nature of the first statement, the second interpretation is somewhat more plausible. If we adopt it, we might then also regard the premise as explanatory. The move is: P, for Q; that is, Q is a reason to believe that P. In addition, Q explains why P is true. As with example (A), (C) tends to confirm Thomas’ view, but is not an ideal example, because it is so weak epistemically – whether interpreted as argument, explanation, or both.

The last example cited, (D), seems best to illustrate Thomas’ claim that the same passage can constitute both explanation and argument. The passage shows that cable television is still at a stage where there are choices to be exercised regarding its development. Four reasons are given for this claim: the history of government regulation in the field of television; the possibility of citizen action; the absence of significant vested interests; and the relative novelty of cable television on the national scene. These are convergent reasons; all give some independent evidence for the claim. Such ‘reasons’, however, may also be regarded as explanatory ‘factors’. Their existence explains why cable television is still open to choice. The explanation has the same structure as the argument. In fact, the argument provides the explanation too. Interestingly, the structure is nothing like that suggested by the deductive nomological model of explanation. We do not have universal or general laws under which the event is subsumed, but rather separate explanatory factors, cited as relevant and as showing how this feature of cable television may be understood.

These cases bear out one of Thomas’ key claims. There are passages that are both argumentative and explanatory, on the same interpretation. This situation can occur because the very statements that provide reasons or evidence that would show the conclusion true also provide an explanation as to why it should be true. The premises can serve also as explanans.

However, such examples do not justify Thomas’ further claim that the same logical criteria suffice to evaluate explanations and arguments. What make the passage a good or plausible argument are not the same conditions that makes it a good or plausible explanation, as numerous other examples have indicated. Both for sound argument and for good explanation, we require valid or legitimate reasoning from some statements to others. But the asymmetry of explanation and argument means that the quite different conditions must be met by justifying premises and explaining statements. Because these conditions are not incompatible, they can be met simultaneously. When that occurs, we find both explanation and argument at once. Statements are able to justify, because in a context where the conclusion is in doubt, they are better known. They are able to explain in virtue of other complex conditions, which entail their being able, in a context, to specify a cause, underlying structure, or purpose that shows how and why the phenomena described in the conclusion-explanandum came to be as they are.

Once a conclusion is accepted, we can look back to the premises as offering an explanation as to why it is true. The very same claims show both that the conclusion is true and why it is true. The same passage constitutes both argument (justification) and explanation, just as Thomas maintained. This can happen because the justifying premises are also statements that are appropriate to explain the fact that is in the conclusion. The audience would, however, have to be convinced of the truth of the conclusion before an explanation as to why it was true would seem necessary.

5. Philosophy, Pedagogy, and Argument-Explanation Asymmetry

Although there do exist some arguments that are explanations and some explanations that are arguments, the distinction between argument and explanation remains important, both pragmatically and epistemically. One way of seeing this is to consider how we differently approach a ‘why’ question, depending on whether we take it to be a request for justificatory argument or for explanation. Suppose that someone asks ‘Why did Jesse Jackson’s 1984 trip to Cuba receive so little media attention?’. If this is taken as a request for an explanation, it will be met by statements trying to specify causes. (Perhaps when the trip occurred, it did not strike media people as important, being regarded as solely propagandistic in intent; perhaps Jackson’s activities were regarded as interesting only insofar as they bore on the 1984 presidential campaign in the United States; perhaps other major world events happened at the same time; perhaps media people were racist; and so on.) On the other hand, if the question is taken as a request for justification, a different kind of answer is called for. The questioner is then asking either for evidence that the trip was indeed given little attention, in effect demanding empirical information about coverage in headlines, inches, location of article, and so on as compared to relevantly similar events; or she is asking for a moral/political justification for giving the trip little space. Thus, what constitutes a proper response and an answer to the question will depend very much on whether we take ‘why’ as making a request for an explanation or an argument.

The significance of the distinction between argument and explanation is again apparent when we consider elliptical arguments and explanations. Suppose, for instance, that someone says he believes in God because he learned religion at his mother’s knee. If ‘because’ is used as explanatory here, we would regard what is said as elliptical for something like the following:

  1. I learned religion at my mother’s knee.
    Missing Explanans: People usually persist in believing those things that they learn at their mother’s knee.
    That is (the cause) why:

  2. I believe in God.

On the other hand, if we take the comments to express an argument we will probably regard that argument as elliptical as well. However, we will complete it in quite a different way, perhaps along such lines as:

  1.  I learned religion at my mother’s knee.
    Missing Premise: Most of what people learn at their mother’s knee is true.
    Therefore, (probably)

  2. God exists.

The comments do a better job of providing a plausible explanation than of providing a justifying argument.(The proposed missing premise is almost certainly false.) The ‘why’ of justification typically asks not for proof that the belief is held, but for reasons purporting to show it true or acceptable.

Noting how the inserted material differs in these cases and how the conclusion of the argument differs from the statement of the explanandum, we can see that the argument/ explanation distinction retains considerable epistemic and pragmatic significance. The force of ‘why’ questions and ‘because’ answers varies, depending on whether we deal with a request for an explanation or for a justification. Different claims are differently relevant, and different standards of success apply. To be sure, reasoning is used both in explanations and in arguments. Without the full context, some responses could be taken as either one or the other. Nevertheless, the distinction retains its pragmatic significance, and the pragmatics of the matter are related to our logical and epistemic appraisal of the result.

Much of what Thomas says is true and important. But the existence of some interesting cases where argument and explanation go on at once does not show that the distinction between justificatory argument and explanation is dispensable. Thomas’ challenge is useful in pointing out the need for greater attention to argument and explanation and in reminding us that reasoning plays a crucial role in both. His examples show that the application of the distinction is not suitable as an early exercise for students unless examples are carefully selected. Background information about context and audience may be required. Textbook accounts of argument and explanation should be made more subtle and qualified, so as to allow that justification and explanation are not mutually exclusive. There exist both cases where these go on together and cases that are borderline and hard to classify as one or the other. We can allow that reasoning is used both in explanation and argument and that the same indicator words are used in each, often with closely parallel roles. We may wish to allow, as Thomas suggests, that logicians who see themselves as appraising reasoning would do well to include explanation as well as argument within the scope of logic.

But given the pragmatic and epistemic differences that exist, the fundamental contrast between explanation and argument retains its pedagogical importance. In a society where people so often tell you how they came to think as they do while ignoring issues of justification, to omit the distinction between argument and explanation from the pedagogy of critical thinking would be a serious mistake. The ‘psychoanalysis’ of thought will presuppose rational argument and critical thinking. It should never replace them.


1. The phrase ‘the fact explained’ refers to the description of the facts or events explained.

2. Recent discussion still uses this Hempel-Oppenheimer account as its starting point, though prevailing opinion is that the covering law model is not adequate. For present purposes, my main concern with the Hempelian account is with its classification of explanation as one type of argument. See Hempel, C.G., ‘Deductive Nomological vs Statistical Explanation’, in H. Feigl and G. Maxwell, (Eds) Minnesota Studies in the Philosophy of Science III, (Minneapolis: University of Minnesota Press, 1962), pp. 98-169; Hempel, C.G., ‘Explanation in Science and in History’, in R. Colodny (Ed.) Frontiers of Science and Philosophy, (Pittsburgh: University of Pittsburgh Press, 1962), pp. 7-33; and Hempel, C.G., Aspects of Scientific Explanation (New York: The Free Press, 1965).

3. This is an unfortunate omission, since analogies are used both in explanations and in arguments, and since the conductive type of argument has its parallel in explanations that proceed by specifying several distinct causal factors.

4. S.N. Thomas, Practical Reasoning in Natural Language (Englewood Cliffs, N.J.: Prentice Hall, 1980. Second Edition), p. 12.

5. Thus the reasoning in an explanation is designed to show how or why F is the case, whereas in an argument reasoning to a conclusion, C, is intended to show that C is the case.

6. Robert Nozick, Philosophical Explanations, (Cambridge, Mass: Harvard University Press, 1981), p. 14. Compare Robert Ennis, ‘Enumerative Induction and Best Explanation’, Journal of Philosophy LXV (1968), pp. 523-528.

7. I discussed transcendental arguments and the role of explanation within them in my doctoral dissertation, A Study of Transcendental Arguments (University of Waterloo, 1971; listed under the name Gertrude R. Kelly.) Kant put it this way: I understand by a transcendental exposition the explanation of a concept, as a principle from which the possibility of other a priori synthetic knowledge can be understood. For this purpose it is required (1) that such knowledge does really flow from the given concept, (2) that this knowledge is possible only on the assumption of a given mode of explaining the concept.’ (Critique of Pure Reason, B41; Norman Kemp Smith translation.)

8. As we will see later, this occurs when the same set of statements satisfies both the conditions required in order to make them justifying premises and the conditions required in order to make them explanatory. These conditions, though distinct, are not incompatible, and thus it may happen that some sets of statements satisfy both at once. Compare Philip Kitcher, ‘Mathematical Rigor: Who Needs It?,’ Nous 15 (1981), pp. 469-93.

9. Thomas, Instructor’s Guide, p. 147.

10. Ibid., p. 148.

11. Ibid., p. 148.

12. Ibid., p. 148.

13. Wesley Salmon, ‘A Third Dogma of Empiricism’, in R. Butts and J. Hintikka, (Eds.), Basic Problems in Methodology and Linguistics (Dordrecht: Reidel, 1977), pp. 149-166. See also Wesley Salmon, ‘Why Ask ‘Why’?’, in Proceedings of the American Philosophical Association 5 (1977-8), pp. 683-701.

14. In ‘Why Ask ‘Why’?’, Wesley Salmon contends on the basis of such cases that explanations require an asymmetry not demanded in arguments. He maintains that this asymmetry is due to the fact that the root notion behind explanation is that of causation.

15. Kitcher, ‘Mathematical Rigor: Who Needs It?’, p. 473.

16. See Wesley Salmon, ‘A Third Dogma of Empiricism’; Bas van Fraasen, ‘The Pragmatics of Explanation’, American Philosophical Quarterly 14 (1975), pp. 143-150; and John Post, ‘Infinite Regresses of Justification and of Explanation’, Philosophical Studies 38 (1980), pp. 31-52.

17. See ‘A Third Dogma of Empiricism’ and ‘Why Ask ‘Why’?’.

18. This point has been noted by several commentators, including R.H. Johnson and J.A. Blair, in Logical Self-Defense. (Toronto: McGraw-Hill Ryerson, 1983.)

19. Compare Kant’s own account in the Critique of Pure Reason (section B41) and my exposition in A Study of Transcendental Arguments, Chapters 2 and 6. Nozick offers a similar account of transcendental argument in Philosophical Explanations, p. 15.

20. In the essay in his instructors’ manual, Thomas claims that examples throughout the text bear out his theory. He mentions that exercise set 1-1B is especially revealing for these purposes. Indeed, by my calculation, fully 9 of 37 exercises in that set could be analyzed as both explanatory and justificatory. Examples discussed here come from this set of exercises.


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Problems in Argument Analysis and Evaluation by Trudy Govier & Windsor Studies in Argumentation is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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