Offering a solution to the skeptical puzzle is a central aim of Nozick's sensitivity account of knowledge. It is well-known that this account faces serious problems. However, because of its simplicity and its explanatory power, the sensitivity principle has remained attractive and has been subject to numerous modifications, leading to a of sensitivity accounts. I will object to these accounts, arguing that sensitivity accounts of knowledge face two problems. First, they deliver a far too heterogeneous picture of higher-level beliefs about (...) the truth or falsity of one's own beliefs. Second, this problem carries over to bootstrapping and Moorean reasoning. Some beliefs formed via bootstrapping or Moorean reasoning are insensitive, but some closely related beliefs in even stronger propositions are sensitive. These heterogeneous results regarding sensitivity do not fit with our intuitions about bootstrapping and Moorean reasoning. Thus, neither Nozick's sensitivity account of knowledge nor any of its modified versions can provide the basis for an argument that bootstrapping and Moorean reasoning are flawed or for an explanation why they seem to be flawed. (shrink)

Keith DeRose’s solution to the skeptical problem is based on his indirect sensitivity account. Sensitivity is not a necessary condition for any kind of knowledge, as direct sensitivity accounts claim, but the insensitivity of our beliefs that the skeptical hypotheses are false explains why we tend to judge that we do not know them. The orthodox objection line against any kind of sensitivity account of knowledge is to present instances of insensitive beliefs that we still judge to constitute knowledge. This (...) objection line offers counter-examples against the claim of direct sensitivity accounts that sensitivity is necessary for any kind of knowledge. These examples raise an easy problem for indirect sensitivity accounts that claim that there is only a tendency to judge that insensitive beliefs do not constitute knowledge, which still applies to our beliefs that the skeptical hypotheses are false. However, a careful analysis reveals that some of our beliefs that the skeptical hypotheses are false are sensitive; nevertheless, we still judge that we do not know them. Therefore, the fact that some of our beliefs that the skeptical hypotheses are false are insensitive cannot explain why we tend to judge that we do not know them. Hence, indirect sensitivity accounts cannot fulfill their purpose of explaining our intuitions about skepticism. This is the hard problem for indirect sensitivity accounts. (shrink)

In this paper, I defend the heterogeneity problem for sensitivity accounts of knowledge against an objection that has been recently proposed by Wallbridge in Philosophia. I argue in, 479–496, 2015) that sensitivity accounts of knowledge face a heterogeneity problem when it comes to higher-level knowledge about the truth of one’s own beliefs. Beliefs in weaker higher-level propositions are insensitive, but beliefs in stronger higher-level propositions are sensitive. The resulting picture that we can know the stronger propositions without being in a (...) position to know the weaker propositions is too heterogeneous to be plausible. Wallbridge objects that there is no heterogeneity problem because beliefs in the weaker higher-level propositions are also sensitive. I argue against Wallbridge that the heterogeneity problem is not solved but only displaced. Only some beliefs in the weaker higher-level propositions are sensitive. I conclude that the heterogeneity problem is one of a family of instability problems that sensitivity accounts of knowledge face and that Wallbridge’s account raises a further problem of this kind. (shrink)

Vogel argues that sensitivity accounts of knowledge are implausible because they entail that we cannot have any higher-level knowledge that our beliefs are true, not false. Becker and Salerno object that Vogel is mistaken because he does not formalize higher-level beliefs adequately. They claim that if formalized correctly, higher-level beliefs are sensitive, and can therefore constitute knowledge. However, these accounts do not consider the belief-forming method as sensitivity accounts require. If we take bootstrapping as the belief-forming method, as the discussed (...) cases suggest, then we face a generality problem. Our higher-level beliefs as formalized by Becker and Salerno turn out to be sensitive according to a wide reading of bootstrapping, but insensitive according to a narrow reading. This particular generality problem does not arise for the alternative accounts of process reliabilism and basis-relative safety. Hence, sensitivity accounts not only deliver opposite results given different formalizations of higher-level beliefs, but also for the same formalization, depending on how we interpret bootstrapping. Therefore, sensitivity accounts do not fail because they make higher-level knowledge impossible, as Vogel argues, and they do not succeed in allowing higher-level knowledge, as Becker and Salerno suggest. Rather, their problem is that they deliver far too heterogeneous results. (shrink)