The Nature of Knowledge – 2
Let us review some of the examples that were problematic for the rival accounts of knowledge.
When there is misleading evidence I am just lucky not to have noticed, then what explains my belief is the fact that I have not noticed this evidence. My believing the dog in that example to be a golden retriever is explained by my not having noticed the misleading mark. My believing as I do is not made significantly more probable by the fact believed, given all the close possible worlds in which I am aware of the misleading evidence.
In the lottery example, the inductive evidence on the basis of which I believe that my ticket will lose does not explain its losing, since the probabilistic connection between that evidence and its losing is screened out by what does explain the latter, the drawing of another ticket. That drawing explains my losing but not my prior belief, which remains explanatorily unconnected to the fact to which it refers.
In regard to problems for the causal theory, the truth of universal propositions helps to explain our belief in them, or it helps to explain the inductive evidence that explains our beliefs. In the case in which I cannot distinguish the cause of my belief from relevant alternatives in the vicinity, the explanation for my belief lies in the broader context and not in the specific cause, just as we do not explain the outbreak of a war by citing only the specific event that triggered it, when any number of equally likely events would have done so in the broader context of latent hostility. In such cases the specific cause does not significantly raise the probability of its effect across close worlds in which alternative causes are also present. To be able to rule out relevant alternatives in claiming knowledge is to be able to rule out alternative explanations for the evidence one has.
In regard to the cases that were problematic for the counterfactual account, what explains the fact that my son is not a knight of the round table, the fact that he lives in the present time and is a tennis player attending Yale, also explains my belief that he is not a Medieval knight. What explains the fact that it is not ninety degrees below zero outside, namely the fact that it is ninety above zero, also explains my belief that it is not subfreezing. Finally, in the aging philosopher example, his belief that the counterfactual analysis is too strong is connected with the evidence that it is too strong in many, although not all, close possible worlds.
In many of these examples, appeal is made to explanatory chains. It suffices for knowledge if what explains my true belief also explains or is explained by the fact to which the belief refers, as long as a certain constraint on these chains is met. Each link in such chains must make later ones more probable. This constraint defeats some purported counter-examples that will not be considered here (see Goldman 1988, pp. 46–50), but its relevance is also clear in the case of knowledge from testimony mentioned earlier in discussing the issue of justification. A person may be justified in believing the testimony of another without any evidence of the other’s expertise or sincerity, as long as there is no evidence that the testimony is likely to be false. Testimony can create its own justification, just as perception can, whether or not the testifier is herself justified in believing her own testimony. But this again simply contrasts justified true belief with knowledge, since one cannot transmit knowledge one does not have. Knowledge from testimony requires an explanatory chain in which the truth of the testimonial evidence enters ultimately into the best explanation for its being given and believed. If I am completely gullible and believe absolutely anything I hear, then I do not gain knowledge from testimony, just as if I see everything as red, then I do not know a red object when I see one. But the last two points imply a third, that a completely gullible person anywhere in the testimonial chain destroys knowledge in the later links. For each link, the fact that the belief was more likely because true must make its transmission more likely to be believed at later links, the constraint mentioned earlier. This does not prevent children from gaining or transmitting testimonial knowledge, since they tend to believe their parents, for example, more than they believe their peers (Schmitt 1999, p. 372).
This completes our brief account of the nature of knowledge. As we shall now see, it will prove to be highly suggestive for the task of determining the scope and structure of knowledge.
Fundamentals of Philosophy – Edited by John Shand