This paper is partly a tribute to Richard Jeffrey, partly a reflection on some of his writings, The Logic of Decision in particular. I begin with a brief biography and some fond reminiscences of Dick. I turn to some of the key tenets of his version of Bayesianism. All of these tenets are deployed in my discussion of his response to the St. Petersburg paradox, a notorious problem for decision theory that involves a game of infinite expectation. Prompted by that paradox, I conclude with some suggestions of avenues for future research.

The question of diachronic coherence, coherence of degrees of belief across time, is investigated within the context of Richard Jeffrey's radical probabilism. Diachronic coherence is taken as fundamental, and coherence results for degrees of belief at a single time, such as additivity, are recovered only with additional assumptions. Additivity of probabilities of probabilities is seen to be less problematic than additivity of first-order probabilities. Without any assumed model of belief change, diachronic coherence applied to higher-order degrees of belief yields the martingale property.

In this essay, I analyze and critique Richard Jeffrey's radical probabilism. The basic theses defining it are examined, particularly the idea that probabilistic coherence involves a kind of “consistency.” The main challenges to Jeffrey's view are (1) that there is an inconsistency between regarding probabilities as subjective and some probabilistic judgments as better than others, and (2) that decision theory so conceived has no normative import. I argue that both of these challenges can be met.

This article agrees with Philip Kitcher that we should aim for a well-ordered science, one that answers the right questions in the right ways. Crucial to this is to address questions of use: Which scientific account is right for which system in which circumstances? This is a difficult question: evidence that may support a scientific claim in one context may not support it in another. Drawing on examples in physics and other sciences, this article argues that work on the warrant of theories in philosophy of science needs to change. Emphasis should move from the warrant of theories in the abstract to questions of evidence for use.

Nearly a half century ago, Thomas Kuhn, Paul Feyerabend, Stephen Toulmin, Norwood Russell Hanson, and others issued a challenge to us philosophers of science to make our field more relevant to actual science. That challenge, over time, has elicited a number of useful responses but very few efforts to situate science within its wider social context when philosophizing about science. The unit of analysis for philosophy of science has tended to remain science-in-a-vacuum. I consider the justifications we offer for this failure, our resources for change, and our prospects if we do change.