AVOIDING COUNTEREXAMPLES

pound of arsenic and died within 24 hours. Consider the following argument, which satisfies Hempel's deductive- nomological criteria for being a correct explanation of her death:

Deductive-Nomological (D-N) Argument

(a) Alice ate a pound of arsenic at time t.

(b) Anyone who eats a pound of arsenic dies within 24 hours.

(c) Alice died within 24 hours of t.

This is a valid deductive argument that contains true prem­ises (a) and (b), among which is a law (b) in Hempel's sense. Therefore, it satisfies Hempel's conditions for being a correct explanation of why Alice died within 24 hours of t. Suppose, however, that Alice was killed not by the arsenic but as a re­sult of being hit by a bus before the arsenic could really have much of an effect. Then, despite Hempel, the explanation is incorrect.

Another type of causal counterexample involves cases in which the cause can be deduced from the effect, but not explained by it. For example,

This body is accelerating.

Whenever a body accelerates there is a force being exerted on the body.

Therefore, there is a force being exerted on this body.

This satisfies Hempel's D-N model, supposing that the two premises are true and the second is a law. But even though we can validly infer the conclusion from the premises, what the conclusion asserts—the presence of a force being exerted on this body—is not correctly explained by the fact that the body is accelerating. Rather, it is the other way around.

To employ my own account for the first example, con­sider the content-question:

Q: Why did Alice die within 24 hours of t?

And, with respect to Q, consider the complete content-giving sentence:

(1) The reason Alice died within 24 hours of t is that she ate a pound of arsenic at t.

On my conception, the fact that Alice ate a pound of arsenic at t, and anyone doing so dies within 24 hours, provides a correct explanation of why Alice died within 24 hours of t if and only if (1) is true. But (1) is false, not true.

Similarly, in the second counterexample, the fact that this body is accelerating, and that any body that is accelerating is being acted on by a force exerted on it, provides a correct explanation of why a force is being exerted on it if and only if

(2) The reason that a force is being exerted on this body is that it is accelerating

is true. Perhaps we would say that the reason it has to be the case that a force is being exerted on this body is that the body is accelerating. But construed as an explanation of why a force is being exerted on this body, (2) is false, not true. Hence, the counterexample is avoided.

What Hempel and other defenders of a deductive model of explanation want to avoid is using explanatory terms such as “reason,” “cause,” and “explanation” in their deduc­tive explanations. For example, no such terms appear in the D-N arguments given earlier. Deductivists seek to define “correct explanation” without using such explanatory terms. What I am suggesting is that this cannot be done if causal counterexamples such as these are to be avoided. You can cite a particular condition that obtained, as the first premise in the D-N argument does. You can cite a true law that governs such a condition, as the second premise does. And the con­dition and the law may together deductively entail the sen­tence describing the event to be explained. But without the assumption that the condition cited actually caused or is causing the event, or that the reason the event occurred or is occurring is that the condition obtained, or that the event occurred because of the condition cited, you cannot con­clude that the explanation offered is correct. By contrast, if p is a complete content-giving sentence with respect to a ques­tion Q, and p is true, then you can conclude that p provides a correct explanation of q.

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