Consider this case:
When Maxwell arrives at work in the morning, he always parks in one of two spots: C8 or D8. Half the time he parks in C8, and half the time he parks in D8. Today Maxwell parked in C8. It’s lunchtime at work. Maxwell and his assistant are up in the archives room searching for a particular document. Maxwell says, “I might have left the document in my car.” The assistant asks, “Mr. Maxwell, is your car parked in space C8? It’s not unheard of for cars to be stolen.” Maxwell thinks carefully for a moment and then responds, “No, my car has not been stolen. It is parked in C8.”
Which of the following options best describes Maxwell?
- He knows that his car is parked in C8. And he knows that his car has not been stolen.
- He does not know that his car is parked in C8. But he does know that his car has not been stolen.
- He knows that his car is parked in C8. But he does not know that his car has not been stolen.
- He does not know that his car is parked in C8. And he does not know that his car has not been stolen.
The epistemic closure principle says, roughly, that if one knows that P, and one knows that if P then Q, and one infers Q, then one knows Q. Some philosophers, most notably Robert Nozick and Fred Dretske, reject the closure principle. However, many epistemologists have claimed that rejecting closure is extremely counterintuitive and radically revisionary. Related to these claims, philosophers have also claimed that conjunctive assertions suggesting a violation of closure are “abominable” and “repugnant.”
So if conventional wisdom in epistemology is correct, then when people consider the question about Maxwell above, the intuitively best answer will not be option 3. Instead, option 3 should seem absurd.
However, as reported in a paper forthcoming in Philosophers’ Imprint, when I tested this case, it turned out that option 3 was viewed as the best option: nearly two-thirds of participants selected it.
We see a similar pattern if we just ask people whether (A) Maxwell knows that his car is parked in the lot, and (B) Maxwell knows that his car has not been stolen. Roughly 80% of people agree with A, while only about 35% of people agree with B.
In light of these results, it seems that closure-denying conjunctions don’t actually strike people as absurd. Moreover, it is highly doubtful that rejecting the epistemic closure principle actually is revisionary.