It is clear that understanding and explanation are related. It is unclear exactly how
they are related. We speak both of explaining-why and understanding-why some event
occurred. Explanations typically produce understanding in those who consider them, and the
sense of increased understanding typically comes from consideration of an explanation.
Consideration of an explanation can, however, fail to produce in someone an increased
level of understanding of the explanandum. Further, the subjective sense of gaining
increased understanding of an event can come from an account that is not the explanation
of that event. Hence, we cannot say that anyone's sense of understanding is either
necessary or sufficient for an account to be an explanation. However, I shall argue, we
cannot completely avoid all reference to understanding in a correct theory of explanation.
This situation presents a pressing problem for philosophical studies of the nature of
explanation, for many theorists relegate the sense of understanding to a strictly
derivative position by claiming that the subjective sense of understanding of an event
comes, under appropriate (articulable) conditions, from consideration of a potential
explanation, and that genuine understanding comes, under appropriate conditions, from
consideration of the true explanation. (See, for example, Hempel 1948, 256-257.) According
to such philosophers we should rely on a proper theory of explanation to delineate
potential explanations from non-explanatory accounts and a delineation of understanding
will follow. I shall argue that this is not a workable option.
One can also express the issue at hand in terms of the relative subjectivity or
objectivity of explanation. Some theorists of explanation state an objectivity criterion
for an account of explanation, and many others implicitly employ one. Wesley Salmon, for
example, states clearly that the identifying criteria for scientific explanations must be
objective, independent of personal, psychological considerations.
First, we must surely require that there be some sort of objective relationship between
the explanatory facts and the fact-to-be-explained. Even if a person were perfectly
content with an explanation of the occurrence of storms in terms of falling barometric
readings, we should still say that the behavior of the barometer fails objectively to
explain such facts. We must, instead, appeal to meteorological conditions. Second, not
only is there the danger that people will feel satisfied with scientifically defective
explanations; there is also the risk that they will be unsatisfied with legitimate
scientific explanations. A yearning for anthropomorphic explanations of all kinds of
natural phenomena for example, the demand that every explanation involve conscious
purposes sometimes leads people to conclude that physics doesn't really explain anything
at all.... Some people have rejected explanations furnished by general relativity on the
ground that they cannot visualize a curved four-dimensional space-time. The psychological
interpretation of scientific explanation is patentlyinadequate (1984, 13).
Salmon's rejection of the psychological interpretation of explanation can, when pushed,
lead one to eliminate all considerations of the subjective sense of understanding from
theorizing about the nature of explanation. I shall argue against this extreme position
and clarify the proper place of considerations of understanding within theorizing about
explanation.
I shall follow the common distinction between a potential explanation and a genuine
explanation, or simply an explanation. A potential explanation is a set of propositions
having all the characteristics of an explanation except, possibly, for truth. A genuine
explanation, then, has all the characteristics of an explanation, and it is true (Hempel
1965, 338).
We should distinguish the mere sense of understanding from genuine understanding. One
can get a sense of understanding from an account that is not wholly true. Genuine
understanding can come only from a genuine explanation. By contrast, the sense of
understanding one gets from a potential explanation containing false statements is not
genuine. We can refer to it as sham understanding. At this point, the distinction between
genuine understanding and sham understanding depends entirely on the distinction between a
true explanation and a merely potential explanation. It is, in this sense, derivative. It
depends on the notion of truth, however, not on any particular theory of explanation.
A sense of understanding can be sham understanding also because it is caused by an
account that is not at all explanatory, regardless of whether its statements are true or
false. Someone can claim to understand an event in virtue of considering a certain set of
propositions but fail to have genuine understanding because those propositions, even if
all true, do not explain the event. Hence, many philosophers would claim that criteria for
what is explanatory (in a theory of explanation) are more basic, and criteria for
understanding derive from them. If one has in hand an acceptable theory of explanation,
one can impugn a sense of understanding as sham understanding either by showing (a) that
it comes from an account that fails to measure up as being explanatory, or (b) that it
comes from an account that is a potential explanation but untrue.
The foregoing description of the relationship between explanation and understanding
sounds unassailable. It seems that one of the necessary conditions for understanding is
that it be caused by consideration of an account that is at least potentially explanatory.
The other necessary condition is that it come from consideration of a true account. One
might go on to explain cases of sham understanding by finding, for example, similarities
(perhaps only superficial similarities) between the accounts that generate the sham
understanding and the genuine explanations of the relevant events or relevantly similar
events. It would then appear that we can explain cases of sham understanding by reference
to the true explanation, which is, to repeat, identified via a proper theory of
explanation.
This cannot be the whole story about the relationship between understanding and
explanation, however. Complications arise from a more careful consideration of the
connections between the sense of understanding and explanation. We have noted that the
sense of understanding need not come from an explanation or even from a potential
explanation. A person might feel a sense of understanding a famine in terms of the
appearance of a comet, for example, but this would be only sham understanding. Similarly,
one can consider the true explanation for an event and fail to gain from it understanding
of why the event occurred. Explanations citing very complex, abstract, or
counter-intuitive principles of physics, for example, might fail to produce a sense of
understanding. Looking only at these two points about the separability of explanation and
understanding leaves the foregoing story about the conceptual primacy of a theory of
explanation undisturbed.
We must note, in addition, that explanation and the sense of understanding cannot be
completely isolated from each other. Consider the claim that some account, some set of
propositions, is the explanation of an event E although no one ever has or could gain a
sense of increased understanding of why E occurred by considering that account. We can
imagine this account consisting only of true propositions, and we can imagine that the
propositions are all topically relevant to E. What reason is there for calling the account
an explanation of E rather than merely an accurate description of some facts related to E?
I can find none.
Consider now an account consisting of propositions relevant to an event E such that
nearly all of the very many psychologically healthy, intelligent, well-educated adults who
think about it claim to gain an increased level of understanding of why E occurred. What
reason could there be for denying that this account is at least a potential explanation of
E? What good reason might one have for insisting that the account is merely a set of
descriptive propositions somehow relevant to E? I can think of none.
I see no reason for calling some account an explanation of E if one has no idea even of
how it could produce in someone an increased sense of understanding of E. And I see no
reason for denying that an account is at least a potential explanation of E if many people
claim that it provides them with an increased sense of understanding of E. A theorist of
explanation might respond that the reasons I stubbornly fail to see come from an
acceptable theory of explanation. We should call an account an explanation, such a
theorist would claim, if it satisfies the criteria of a preferred theory of explanation,
although we see no way for the account to increase anyone's understanding of the
explanandum. Likewise, if an account fails to satisfy the conditions of some preferred
theory of explanation, then it does not count as a potential explanation, even if many
people seem to receive greatly increased understanding from it.
This last bold assertion of the conceptual priority of explanation over understanding
clarifies why this strategy ultimately fails. To accept the ruling from a theory of
explanation that a certain account is explanatory when one gains no sense of understanding
from it, one needs reasons for accepting that theory of explanation as a correct theory.
We therefore need to examine how a theory of explanation is justified, or defended against
competing theories of explanation. The justification of a theory of explanation relies
essentially, I shall argue, on using the sense of understanding as a guide to what
accounts are potentially explanatory and what accounts are not.
There have been competing theories of explanation. Carl Hempel (1948, 1965) proposed
the deductive-nomological model, the inductive-statistical model, and the
deductive-statistical model as collectively capturing all the forms of scientific
explanation. Richard Jeffrey (1969), James Greeno (1970), and Wesley Salmon (1970, 1971)
objected to Hempel's claim that scientific explanations must take the form of an argument.
Each proposed a competing theory of explanation (statistical-relevance or
information-theoretic) as a correct account of scientific explanation. Later, Salmon
revised his thinking about scientific explanation and proposed his causal theory of
explanation with a statistical-relevance basis (Salmon 1984), thereby joining a long list
of causal theorists of explanation. Criticisms and competing refinements have come from
Peter Railton (1978, 1981), Philip Kitcher (1976, 1981, 1989), Peter Achinstein (1983),
Bas van Fraassen (1980, chap. 5), and many others. The history of competing theories of
explanation is complex, but a common theme lies in the methodology of defending a theory.
A classic example will clearly illustrate the standard method of argumentation regarding
theories of explanation.
The case of the flagpole and its shadow is an argument against Hempel's
deductive-nomological theory of explanation. The example is attributed to Sylvain
Bromberger, although he claims never to have published it (1992, 8). The argument states
that one can deduce the height of a flagpole from the length of its shadow and the
elevation of the sun (and appropriate laws regarding the propogation of light). The
argument shows that such a deduction satisfies the conditions put forth in Hempel's D-N
model of explanation for an acceptable scientific explanation of the height of the
flagpole. The argument concludes that, since the length of its shadow clearly does not
explain the height of the flagpole, Hempel's model does not present a set of sufficient
conditions for scientific explanation.
The method illustrated here is the familiar method of counterexample. One argues
against a theory of explanation either by presenting a set of propositions satisfying the
criteria of the theory although it is not an explanation, or by presenting an explanation
that fails to fit the criteria of the theory. The former method shows that the theory does
not present a set of sufficient conditions for explanation, the latter shows that the
theory does not present necessary conditions for an explanation. This method obviously
requires some determination, independent of the theory under dispute, that the
counterexample either is or is not an explanation. This determination depends, I claim, on
the presence or absence of a sense of understanding generated in the counterexample.
A similar point applies to the defense of a theory of explanation. Theorists typically
argue for their theory of explanation by demonstrating how it applies to a stock set of
examples of explanation and a stock set of non-explanations, giving the right
determination in every case. One might argue for the D-N model of explanation, for
example, by showing that it does capture the sense in which one can explain the length of
the flagpole's shadow by deducing it from the height of the flagpole, the elevation of the
sun, and the appropriate laws. Such a defense of a theory of explanation must rely on some
prior set of criteria for distinguishing explanations from non-explanations, and this set
of criteria must be independent of the theory of explanation being tested in order to
avoid an obvious circularity in the justification of the theory. It is of no use to show
that one's theory of explanation succeeds in counting all explanations in a certain sample
as explanations and all non-explanations in a certain sample as non-explanations if the
samples were prepared using that theory of explanation itself.
The determination of stock examples of explanation and non-explanation, independent of
a theory of explanation, must be based on the sense of understanding one gets from
explanations but not from non-explanations. This follows from the peculiar nature of
explanations as a class of statements. Explanations consist of descriptive statements.
There is dispute about whether an explanation must take the form of an argument, whether
an explanation must invoke laws, whether an explanation must cite causes. And there are
many other disputes about the form explanations must take. To my knowledge, however, there
is no dispute over the claim that explanations must consist of descriptive statements.
They do not contain normative claims. They do not consist of questions (except perhaps as
elliptical expressions of statements). They do not consist of imperative statements. A
true explanation consists only of true descriptive propositions. Consequently, we cannot
identify explanations as a class by syntactic means similar to the way we distinguish
normative claims, questions, or orders.
Explanation is not merely true description, however. That is, explanation is
description of a particular sort. So we cannot identify explanations as a class just by
the syntactic means we use to distinguish descriptive statements as a class together with
the semantic distinction of truth.
A prima facie determination that a set of propositions is explanatory for some event
must rely on intuitions about the potential for those statements to produce a sense of
understanding of why the event occurred. The determination cannot be made merely on the
basis of topical relevance. For any event, there are many sets of topically relevant and
true descriptive claims that are not explanatory. Using any criterion based on causal
relevance, considerations of statistical relevance, unification, or any similarly
controversial features will clearly beg the question against some theories of explanation.
We require a more nearly neutral means of identifying explanations prior to theorizing,
and this can come only from the subjective and, to some extent, relative sense of
understanding.
The ineliminable function of a sense of understanding in theorizing about the nature of
explanation poses the threat of a dangerous sort of subjectivity infecting our thinking
about explanation. Subjectivity is indeed dangerous here, given the central place of
inference to the best explanation in all scientific theorizing. The fear is that our
distinguishing explanatory from non-explanatory hypotheses (and our assigning considerably
more importance to explanatory hypotheses in science) might be based ultimately in a
species-specific peculiarity in the way we humans happen to process information, rather
than in any objective and natural features of the world. This fear is not unfounded, for
peculiar conceptions of the nature of explanation have led people to accept bizarre views
of the world. Some metaphysical theories, regarded as untenable even by strong defenders
of metaphysics generally, have been defended on the basis of highly idiosyncratic views
about what is required for adequate explanation of some aspect of experience.
This fear can be allayed, however. The subjective sense of understanding is necessary
as an initial guide to the nature of explanation, but it is by no means the final word.
There is a complex system of social correction of notions of explanation. An initial
notion of explanation leads to and supports theories about the world by way of inference
to the best explanation. But theories about the world in turn refine our notions of
explanation. We expect that this process of refinement and correction leads us closer to
an objectively accurate picture of the world and of the natural relationship of
explanation. Filling in the details of how this process of refinement and correction works
requires much work and obviously extends far beyond the scope of this paper. We must
nonetheless fill in these details in order to secure objective validity for an inferential
process that necessarily originates in relatively unconstrained subjective impressions but
also serves to ground our theoretical advances in a scientific understanding of the world.
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