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Unformatted text preview: Fall 2006 Sherri Roush 1 Williamson, Knowledge and its Limits , Chapter 7, “Sensitivity” I. Stuff about counterfactuals II. Sensitivity and Skepticism (and Closure) III. Sensitivity and Methods (and Closure) III. Ship example (and Closure) IV. Sensitivity and Broad Content I. Stuff about counterfactuals a. Note that in the hardback version in the first paragraph of this chapter, there’s a mistake where TW argues by example that sensitivity does not imply safety. This is true, but his example goes in the wrong direction, to show that safety doesn’t imply sensitivity (which is also true). An example that serves the purpose is a necessary falsehood. (The problem is corrected in the paperback.) More interestingly, though this fact, and the converse that safety does not imply sensitivity, are often cited that is a bit of missing the forest for the trees, since in the domain of true belief sensitivity provides uniform probabilistic assurances of safety (but not the converse), and beliefs that aren’t true aren’t knowledge anyway, before we get to the safety or sensitivity requirement on knowledge. (See TT , chapter 4: “Sensitivity and Safety: No Trade-off”, pp. 123-124.) b. TW claims on page 148 that “Any counterfactual conditional entails the corresponding material conditional, so in particular –p -Bp entails –p ⊃-Bp.” Since the material conditional is equivalent to – (-p . Bp), this implies that if a belief satisfies sensitivity then (in the actual world) it’s not false (but true), in other words: “S sensitively believes p only if p is true”. But this implication should seem bizarre, because it makes truth a variable that’s not independent of the X condition on knowledge which is the classic way to define infallibilism. However, the tracking view was always understood as a fallibilist view, the obvious symptom of which is that the counterfactual only requires its consequent to be true in a subset of –p worlds. In those far off worlds where –p holds the counterfactual requires nothing about your beliefs so you might have been wrong if one of those worlds had been the case. You can satisfy the sensitivity criterion while you still might have been wrong—one notion of fallibilism—and yet because of properties of counterfactuals satisfying the sensitivity criterion implies your belief is true—a rejection of the other standard notion of fallibilism, that of truth as an independent variable. So there are two notions of fallibility at work that come apart here. However, notice what’s going on: the only reason that it follows from satisfying sensitivity for p that p is true in the actual world is that you had to specify that p was true in the actual world in order to evaluate the counterfactual, in order to orient that evaluation. So it falls out essentially because it was put in, not because what your dispositions to believe in –p worlds give you is protection against the possibility of believing p falsely. the possibility of believing p falsely....
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- Fall '06
- Sensitivity, Counterfactual conditional, Material conditional, Conditional sentence, Gunderson, Sherri Roush