- In the beginning, there was the DN (Deductive Nomological) model of explanation, articulated by Hempel and Oppenheim (1948). According to DN, scientific explanation is subsumption under natural law. Individual events are explained by deducing them from laws together with initial conditions (or boundary conditions), and laws are explained by deriving them from other more fundamental laws, as, for example, the simple pendulum law is derived from Newton's laws of motion.
- It is well-known that DN is vulnerable to a wide variety of counterexamples (e.g., Kim, 1962; Salmon 1998). As a result, DN is not widely defended. But it is, I think, still widely believed that scientific explanation is subsumption under law. This is something of a scandal: Given DN's miserable track record in spite of spirited defense by many ingenious believers, one is led to ask why so many cleave so faithfully to a doctrine that has proved so indefensible?
- There are two factors that work to keep DN in place. First, there is the fact that every experimental paper one picks up involves the explanation of some data by appeal to some hypothesis or other. It is tempting to conclude that philosophers' continued failure to articulate this practice in some defensible way is a point against philosophers, not against DN. And second, there is the fact that there is no widely understood and compelling alternative to DN on the market. If cognitive psychology has taught us anything, it is that no one willingly gives up a well-worn idea without having something to put in its place. I propose to examine these two factors in turn.
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