Mattias Skipper

Many theories of rational action are predicated on the idea that what it is rational to do in a given situation depends, in part, on what it is rational to believe in that situation. In short: they treat epistemic rationality as explanatorily prior to practical rationality. If they are right in doing so, it follows, on pain of explanatory circularity, that epistemic rationality cannot itself be a form of practical rationality. Yet, many epistemologists have defended just such a view of epistemic rationality. According to them, there is no such thing as a distinctively epistemic form of rationality which could be explanatorily prior to practical rationality. Rather, they maintain, there is just one form of rationality—practical rationality—of which epistemic rationality is a species. What to make of this conflict? The aim of this paper is to motivate a view about the relationship between epistemic and practical rationality which resolves the conflict in a way that should be attractive to both sides. The central idea is to ground both epistemic and practical rationality in an independently motivated notion of evidential probability which is itself to be understood in non-normative terms. Doing so, I argue, allows us to unify epistemic and practical rationality in a way that does justice to the idea that what it is rational to do depends, in part, on what it is rational to believe; and to do so in a way that avoids explanatory circularity.

Orthodox Bayesianism is a highly idealized theory of how we ought to live our epistemic lives. One of the most widely discussed idealizations is that of logical omniscience: the assumption that an agent’s degrees of belief must be probabilistically coherent to be rational. It is widely agreed that this assumption is problematic if we want to reason about bounded rationality, logical learning, or other aspects of non-ideal epistemic agency. Yet, we still lack a satisfying way to avoid logical omniscience within a Bayesian framework. Some proposals merely replace logical omniscience with a different logical idealization; others sacrifice all traits of logical competence on the altar of logical non-omniscience. We think a better strategy is available: by enriching the Bayesian framework with tools that allow us to capture what agents can and cannot infer given their limited cognitive resources, we can avoid logical omniscience while retaining the idea that rational degrees of belief are in an important way constrained by the laws of probability. In this paper, we offer a formal implementation of this strategy, show how the resulting framework solves the problem of logical omniscience, and compare it to orthodox Bayesianism as we know it.

Should you always be certain about what you should believe? In other words, does rationality demand higher-order certainty? First answer: Yes! Higher-order uncertainty can’t be rational, since it breeds at least a mild form of epistemic akrasia. Second answer: No! Higher-order certainty can’t be rational, since it licenses a dogmatic kind of insensitivity to higher-order evidence. Which answer wins out? The first, I argue. Once we get clearer about what higher-order certainty is, a view emerges on which higher-order certainty does not, in fact, license any kind of insensitivity to higher-order evidence. The view as I will describe it has plenty of intuitive appeal. But it is not without substantive commitments: it implies a strong form of internalism about epistemic rationality, and forces us to reconsider standard ways of thinking about the nature of evidential support. Yet, the view put forth promises a simple and elegant solution to a surprisingly difficult problem in our understanding of rational belief.

Epistemic instrumentalists think that epistemic normativity is just a special kind of instrumental normativity. According to them, you have epistemic reason to believe a proposition insofar as doing so is conducive to certain epistemic goals or aims—say, to believe what is true and avoid believing what is false. Perhaps the most prominent challenge for instrumentalists in recent years has been to explain, or explain away, why one’s epistemic reasons often do not seem to depend on one’s aims. This challenge can arguably be met. But a different challenge looms: instrumental reasons in the practical domain have various properties that epistemic reasons do not seem to share. In this chapter, we offer a way for epistemic instrumentalists to overcome this challenge. Our main thesis takes the form of a conditional: if we accept an independently plausible transmission principle of instrumental normativity, we can maintain that epistemic reasons in fact do share the relevant properties of practical instrumental reasons. In addition, we can explain why epistemic reasons seem to lack these properties in the first place: some properties of epistemic reasons are elusive, or easy to overlook, because we tend to think and talk about epistemic reasons in an ‘elliptical’ manner.

We often have reason to doubt our own ability to form rational beliefs, or to doubt that some particular belief of ours is rational. Perhaps we learn that a trusted friend disagrees with us about what our shared evidence supports. Or perhaps we learn that our beliefs have been afflicted by motivated reasoning or other cognitive biases. These are examples of higher-order evidence. While it may seem plausible that higher-order evidence should impact our beliefs, it is less clear how and why. Normally, when evidence impacts our beliefs, it does so by virtue of speaking for or against the truth of theirs contents. But higher-order evidence does not directly concern the contents of the beliefs that they impact. In recent years, philosophers have become increasingly aware of the need to understand the nature and normative role of higher-order evidence. This is partly due to the pervasiveness of higher-order evidence in human life. But it has also become clear that higher-order evidence plays a central role in many epistemological debates, spanning from traditional discussions of internalism/externalism about epistemic justification to more recent discussions of peer disagreement and epistemic akrasia. This volume brings together, for the first time, a distinguished group of leading and up-and-coming epistemologists to explore a range of issues about higher-order evidence.

In this paper, we present a new semantic framework designed to capture a distinctly cognitive or epistemic notion of meaning akin to Fregean senses. Traditional Carnapian intensions are too coarse-grained for this purpose: they fail to draw semantic distinctions between sentences that, from a Fregean perspective, differ in meaning. This has led some philosophers to introduce more fine-grained hyperintensions that allow us to draw semantic distinctions among co-intensional sentences. But the hyperintensional strategy has a flip-side: it risks drawing semantic distinctions between sentences that, from a Fregean perspective, do not differ in meaning. This is what we call the ‘new problem’ of hyperintensionality to distinguish it from the ‘old problem’ that faced the intensional theory. We show that our semantic framework offers a joint solution to both these problems by virtue of satisfying a version of Frege’s so-called ‘equipollence principle’ for sense individuation. Frege’s principle, we argue, not only captures the semantic intuitions that give rise to the old and the new problem of hyperintensionality, but also points the way to an independently motivated solution to both problems.