The Humean Thesis on Belief

Degrees of Belief, 2009

The Philosophical Review 123/2 (2014), 131-171.

This paper develops a joint theory of rational (all-or-nothing) belief and degrees of belief. The theory is based on three assumptions: the logical closure of rational belief; the axioms of probability for rational degrees of belief; and the so-called Lockean thesis, in which the concepts of rational belief and rational degree of belief figure simultaneously. In spite of what is commonly believed, we will show that this combination of principles is satisfiable (and indeed non-trivially so), and that the principles are jointly satisfied if and only if rational belief is equivalent to the assignment of a stably high rational degree of belief. Although the logical closure of belief and the Lockean thesis are attractive postulates in themselves, initially this may seem like a formal “curiosity”; however, as we are going to argue in the rest of the paper, a very reasonable theory of rational belief can be built around these principles which is not ad hoc but which has various philosophical features that are plausible independently.

2019

There are two ways of representing rational belief: qualitatively as yes-or-no belief, and quantitatively as degrees of belief. Standard rationality conditions are: (i) consistency and logical closure, for qualitative belief, (ii) satisfaction of the probability axioms, for quantitative belief, and (iii) a relationship between qualitative and quantitative beliefs in accordance with the Lockean thesis. In this paper, it is shown that these conditions are inconsistent with each of three further rationality conditions: fallibilism, open-mindedness, and invariance under independent conceptual expansions. Restrictions of the Lockean thesis that have been suggested in the literature cannot remove the inconsistency. In the outlook we discuss two alternative ways of dealing with this problem: restricting conjunctive closure or going for a dual system account.

Synthese, 1998

If the logic of belief changes is extended to cover belief states which contain both factual and normative beliefs, it is easily shown that a change of a factual belief (an 'Is') in a mixed belief state can imply a change of a normative belief (an 'Ought') in the same state. With regard to Hume's so-called 'Is-Ought problem', this means that one has to distinguish its statics from its dynamics. When this is done, it becomes clear that changes of factual beliefs can, for rational reasons, have far-reaching normative consequences. Similarly, a change of a factual belief can imply a change of a value belief.

In this paper, I explore the question of whether the expected consequences of holding a belief can affect the rationality of doing so. Special attention is given to various ways in which one might attempt to exert some measure of control over what one believes and the normative status of the beliefs that result from the successful execution of such projects. I argue that the lessons which emerge from thinking about the case of belief have important implications for the way we should think about the rationality of a number of other propositional attitudes, such as regret, desire, and fear. Finally, I suggest that a lack of clarity with respect to the relevant issues has given rise to a number of rather serious philosophical mistakes.

I give original arguments for the thesis that one believes a proposition only if one's credence in it is 1, as well as respond to several objections to that thesis. Belief implies having a credence of 1 because of the connections between assertoric representation, possibility, and probability.

Philosophical Review

It is plausible that there are epistemic reasons bearing on a distinctively epistemic standard of correctness for belief. It is also plausible that there are a range of practical reasons bearing on what to believe. These theses are often thought to be in tension with each other. Most significantly for our purposes, it is obscure how epistemic reasons and practical reasons might interact in the explanation of what one ought to believe. We draw an analogy with a similar distinction between types of reasons for actions in the context of activities. The analogy motivates a two-level account of the structure of normativity that explains the interaction of correctness-based and other reasons. This account relies upon a distinction between normative reasons and authoritatively normative reasons. Only the latter play the reasons role in explaining what state one ought to be in. All and only practical reasons are authoritative reasons. Hence, in one important sense, all reasons for belief are practical reasons. But this account also preserves the autonomy and importance of epistemic reasons. Given the importance of having true beliefs about the world, our epistemic standard typically plays a key role in many cases in explaining what we ought to believe. In addition to reconciling (versions of) evidentialism and pragmatism, this two-level account has implications for a range of important debates in normative theory, including the interaction of right and wrong reasons for actions and other attitudes, the significance of reasons in understanding normativity and authoritative normativity, the distinction between ‘formal’ and ‘substantive’ normativity, and whether there is a unified source of authoritative normativity.

Foundations of Science, 2012

Some philosophers have argued that a standard of correctness is constitutive of the concept or the essence of belief. By this claim they mean, roughly, that a mental state is a belief partially in virtue of being correct if and only if its content is true. In this paper I provide a new argument in support of the constitutivity of the correctness standard for belief. I first argue that the standard expresses a conceptual necessity. Then I argue that, since conceptual necessities are such in virtue of some concept, the standard must also be necessary in virtue of some concept. Finally, I provide an argument by exclusion to the effect that the standard is necessary in virtue of the concept of belief.