As it is impossible to cover every possible variation in the space I have available, I shall cover what I take to be versions representative of the most dominant theories in epistemology. One version of permissivism says that people may adopt different epistemic standards because they have different cognitive abilities. The existence of these different cognitive abilities means that different epistemic standards will be maximally truth-conducive for different people. In this chapter, I shall be addressing Simpson’s account, which depends on people being cognitively imperfect in one way or other.
Simpson illustrates his account of permissivism with a rather lengthy case he refers to as Detective. I shall reproduce the case in full.
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Detective: “Veronica Mars and Nancy Drew are investigating a crime for which X and Y are the prime suspects. After thoroughly reviewing the same body of relevant evidence, Mars believes it’s 70% likely X is the culprit and 30% likely Y is the culprit, whereas Drew believes it’s 30% likely X is the culprit and 70% likely Y is the culprit… Suppose firstly that Mars and Drew employ different epistemic standards, i.e. they use different methods for assessing and interpreting their evidence in order to form their beliefs. Suppose, for instance, that they have different methods for evaluating the probative force of testimonial evidence, a type of evidence that’s often an important part of the data they examine as detectives. Mars is excellent at recognizing insincere testimony – she’s very sensitive to various subtle verbal and non-verbal tell-tale markers of insincerity – and thus she interprets different instances of testimony differently, ascribing a different probative force to insincere testimonial evidence. Drew is not very good at identifying insincere testimony, but she is excellent at making holistic, gestalt assessments of the combined probative implications of large bodies of disparate evidence. So unlike Mars, Drew doesn’t pre-sort the testimonial evidence, based on its sincerity. Where Mars reviews the testimonial evidence in sequence, identifying each item’s probative force in its own right, Drew reviews all testimonial evidence in the same light, and assesses the probative force of the testimonial data as a set. Mars applies her standards because she’s cognitively well-equipped to apply them. She has the kind of perceptual and attentional abilities that enable her to accurately judge the sincerity of testimony. In a similar way, Drew is cognitively well-equipped to apply her standards. She has a particular imaginative facility that enables her to formulate credible explanatory narratives, based on gestalt interpretations of diverse bodies of evidence... Although Mars and Drew are working together for the first time, they have a long track-record of working independently on other cases. And in light of their track-records, both of them have good reason to believe that when they apply their own epistemic standards, in forming beliefs about cases relevantly similar to the case at hand, they are very likely to get the answer right. In short, each of them is in the position of (i) having a combination of cognitive abilities and epistemic standards which reliably generates
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accurate beliefs, and (ii) having good reason to believe that this is the case.” (Simpson 2017)
Simpson argues that this case provides an example of how people with different but equally reliable cognitive capacities could adopt different epistemic standards. If Simpson is correct, people who have different cognitive capacities could adopt different standards and therefore have different responses to the evidence which were nevertheless still rational. Simpson’s account relies on the presumption that the epistemic standard best suited for each person is maximally truth-conducive for that person. If Nancy Drew were to try to apply Veronica Mars’ standards she would do less well because she would do badly at evaluating the sincerity of the testimony. Similarly, Veronica Mars would also perform sub-optimally if she applied Nancy Drew’s standards, as she is prone to make mistakes when trying to assess the probative force of the evidence as a whole. Both standards play to their respective agents’ strengths and mitigate their weaknesses.
However, it is this aspect of the situation which undermines the rationality of both detectives’ responses. Both Nancy Drew and Veronica Mars fail to respond perfectly well to all their evidence because both have weaknesses: parts of the evidence which they are unable to reliably assess well. To see why, consider an amalgamation of Nancy Drew and Veronica Mars: Nancy Mars. Nancy Mars has both Nancy Drew’s and Veronica Mars’s weaknesses: she is unable to reliably assess the sincerity of testimony and evaluate the evidence as a whole. Nancy Mars is clearly less reliable than both Nancy Drew and Veronica Mars. Nancy Mars is less reliable than Veronica Mars due to the reason that she is unable to reliably assess the sincerity of testimonial evidence; hence, she tends to overestimate the probative force of testimony from insincere people and underestimate the force of testimony from those who are sincere. Since Nancy Mars differs from Veronica Mars in just this one respect, the former is clearly less reliable than the latter. Plausibly, to over or underestimate the strength of a given piece of evidence is, by definition, to make a mistake in reasoning. If reasoning well necessarily involves forming beliefs in proportion to the strength of the evidence, then forming beliefs that deviate from what the evidence points to is going to be a mistake. As I shall be arguing in the following sections, if a belief can only be formed on the basis of a mistake, then it is not rational given the evidence.
Since Veronica Mars is just as reliable as Nancy Drew, Nancy Mars must be less reliable than Nancy Drew. The only difference between Nancy Mars and Nancy
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Drew is that the latter evaluates her evidence as a whole, whereas the former evaluates her evidence piece by piece. Since evaluating the evidence piece by piece is less reliable than evaluating it as a whole, evaluating it piece by piece must involve in at least some cases mis-estimating the strength of the evidence as a whole. The assumption here is that to evaluate one’s evidence properly is to evaluate it in a maximally truth-conducive manner. I shall evaluate this assumption later in this chapter, but, for now, if it is true, then Nancy Mars must make at least some mistakes in reasoning by evaluating her evidence piece by piece rather than as a whole.
If evaluating one’s evidence piece by piece results in a mistake in a given case, then Veronica Mars would make a mistake in reasoning in that case. Similarly, if failing to account for the sincerity of testimony is a mistake, then Nancy Drew also makes a mistake whenever she applies her epistemic standards. As such, since they both make mistakes in reasoning, their disagreement cannot be rational. Notably, they must be substantive mistakes because they involve misestimating the overall strength of the evidence. The doxastic attitude they end up with arguably does not fit the evidence. If, on the other hand, they were to properly evaluate the evidence by both reliably assessing the sincerity of testimony and evaluating the evidence as a whole, there seems to be no particular reason why they would disagree.
Resisting this argument requires showing that evaluating the evidence piece by piece and failing to assess the sincerity of testimony are not mistakes in reasoning; or even if they are mistakes, do not render the resultant belief irrational. However, if they are not mistakes then it would be permissible for Nancy Drew and Veronica Mars to adopt Nancy Mars’s epistemic standard. Yet if more than one epistemic standard was permissible for any agent, it would, as discussed in Chapter 4, be arbitrary as to why she uses one standard rather than another. Moreover, as discussed in the same chapter, the facts which ground evidential support cannot include the agent’s epistemic standard. If so, more than one epistemic standard cannot be permissible for any given agent. What is implicit in Simpson’s argument is the claim that Nancy Drew can permissibly not assess the sincerity of testimony because she is not able to reliably do so. Similarly, Veronica Mars can permissibly assess the evidence piece by piece because she is incapable of assessing it as a whole.
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What is implicit in the Detective case is the idea that the reason why people can have different epistemic standards when they have different cognitive capacities is that they can permissibly lower their epistemic standards in response to their own cognitive limitations. Thus, since Nancy Drew cannot reliably assess the sincerity of testimony, she ought to adopt an epistemic standard according to which she should ignore all evidence pertaining to sincerity. If, on the other hand, people’s epistemic standards need not be lowered in response to cognitive limitations, there would be no reason to think that a standard according to which Nancy Drew need not assess the sincerity of testimony is appropriate for her just because she cannot reliably assess the sincerity of testimony. Likewise, there would be no reason to think that a standard according to which the agent need not evaluate the evidence as a whole is permissible for Veronica Mars.