How do we ascribe subjective probability? In decision theory, this question is often addressed by representation theorems, going back to Ramsey (1926), which tell us how to define or measure subjective probability by observable preferences. However, standard representation theorems make strong rationality assumptions, in particular expected utility maximization. How do we ascribe subjective probability to agents which do not satisfy these strong rationality assumptions? I present a representation theorem with weak rationality assumptions which can be used to define or measure (...) subjective probability for partly irrational agents. (shrink)

This paper aims to flesh out the celebrated notion of reflective equilibrium within a probabilistic framework for epistemic rationality. On the account developed here, an agent's attitudes are in reflective equilibrium when there is a certain sort of harmony between the agent's credences, on the one hand, and what the agent accepts, on the other hand. Somewhat more precisely, reflective equilibrium is taken to consist in the agent accepting, or being prepared to accept, all and only claims that follow from (...) a maximally comprehensive theory that is more probable than any other such theory. Drawing on previous work, the paper shows that when an agent is in reflective equilibrium in this sense, the set of claims they accept or are prepared to accept is bound to be logically consistent and closed under logical implication. The paper also argues that this account can explain various features of philosophical argumentation in which the notion of reflective equilibrium features centrally, such as the emphasis on evaluating philosophical theories holistically rather than in a piecemeal fashion. (shrink)

There is some consensus on the claim that imagination as suppositional thinking can have epistemic value insofar as it’s constrained by a principle of minimal alteration of how we know or believe reality to be – compatibly with the need to accommodate the supposition initiating the imaginative exercise. But in the philosophy of imagination there is no formally precise account of how exactly such minimal alteration is to work. I propose one. I focus on counterfactual imagination, arguing that this can (...) be modeled as simulated belief revision governed by Laplacian imaging. So understood, it can be rationally justified by accuracy considerations: it minimizes expected belief inaccuracy, as measured by the Brier score. (shrink)

In response to two trenchant objections, radical subjective Bayesianism has been widely rejected. In this paper, I seek, if not to rehabilitate subjectivism, at least to show its critic what is attractive about the position. I argue that what is at stake in the subjectivism/anti-subjectivism debate is not, as is commonly thought, which norms of rationality are true, but rather, the conception of rationality that we adopt: there is an alternative approach to the widespread telic approach to rationality, which I (...) call the poric approach, on which subjectivism is an attractive position. I then argue that the poric approach—and therefore subjectivism—cannot be easily dismissed. (shrink)

According to the Classical Pessimistic Induction (CPI), otherwise positive features like predictive and explanatory success actually cast doubt on theories that display them. After all, they negatively correlate with truth. From this historical track record, it is inferred that current best theories are probably not (even approximately) true. The CPI is often wielded against realists about science, but others like Hume (1757), Pareto (1935), and Hájek (2007) extend it to philosophical theories more generally. In this paper, I unveil a priori (...) refutations that defang the CPI in all its guises. To date, treatments of this topic typically assume the following: if the historical proportion of false theories increases, then it has increasingly negative bearing against realism. I show that this assumption is false. I identify three types of problems for the CPI, each attaching to some interpretation or other. The first problem is that the CPI violates a universal adequacy condition on the confirmation relation that restricts the relationship between entailment and disconfirmation. The second problem is that the induction’s target hypotheses preclude the track record from instantiating a list of epistemically significant properties that empirical information is supposed to afford. The third problem is that it is constitutively impossible for the CPI to have random samples; this implies that even the use of randomization procedures cannot help. In sum: my refutation is novel, accessible by pure reflection, and quite general. (shrink)