Evidence, experience and decision

The central thread of Comesaña’s book is his defense of Experientialism, the thesis that “our empirical evidence is constituted by what we are basically justified in believing through experience” (2020, 3). When coupled with the plausible claim that we can be basically (i.e. non-inferentially) justified in believing falsehoods, we get the result that false propositions can be part of our empirical evidence.

Comesaña’s account of evidence contrasts with (i) those who think that our empirical evidence consists in either experiences or in true propositions about our experience (such as propositions of the form: it looks to be that case that p) and also (ii) with those who think that a proposition only gets to be part of our evidence by being known. A central motivation for Experientialism over type-(i) views is that the kind of evidence allowed by the latter does not rule out such exotic hypotheses as that one is a brain a vat. (After all, truths about how things look will be quite compatible with such exotica.) Thus, as Comesaña sees it, type-(i) views do not comport with the way that our evidence serves to narrow down the space of possibilities when we engage in theory building and decision making. Turning to type-(ii) views, a salient drawback is that they seem to posit counterintuitive asymmetries in rationality. Consider two agents with the same background knowledge and matching experiences, one of whom perceives that there is a real candy in from of them, one of whom is looking at a marble that appears just like a real candy. As Comesaña points out, it is natural to think that these agents are equally rational at the level of both thought and action when they reach out and pop the candy-looking item in their mouth. But if we impose an evidential asymmetry – as knowledge-theoretic views of evidence are apt to–this will militate in favor of asymmetries of rationality, since one of the agents will have richer evidence and thus better support for various candy-oriented beliefs and actions.

Comesaña’s defense of Experientialism is rich and provocative, and worthy of detailed study. I shall confine my remarks to some central and important issues raised by his vision.

© The Author(s), under exclusive licence to Springer Nature B.V. 2023.