Graham Oddie

Why should a Bayesian bother performing an experiment, one the result of which might well upset his own favored credence function? The Ramsey-Good theorem provides a decision theoretic answer. Provided you base your decision on expected utility, and the the experiment is cost-free, performing the experiment and then choosing has at least as much expected utility as choosing without further ado. Furthermore, doing the experiment is strictly preferable just in case at least one possible outcome of the experiment could alter your choice of options. That is, you should pursue the information just in case it could make a difference to what you do. The problem remains, however, why one should do an experiment when nothing of much practical consequence hangs in the balance. One possibility here is to invoke the pure cognitive utility of states. It is shown that one constraint on cognitive value (what I call cogency) guarantees the value of learning: from a cognitive point of view you are justified in performing an experiment if the outcome of the experiment could make a different to what you think. A bonus of the basic framework is that it provides a new decision theoretic argument for the rationality of conditionalization.

The core of the truthmaker research program is that true propositions are made true by appropriate parts of the actual world. This idea seems to give realists their best shot at capturing a robust account of the dependence of truth on the world. For a part of the world to be a truthmaker for a particular it must suffice for, or necessitate, the truth of the proposition. There are two extreme and unsatisfactory truthmaker theories. At one extreme any part of the world (up to and including the whole world) that suffices for a proposition is deemed to be a truthmaker for that proposition. At the other extreme there is only one truthmaker that can do the job, and that is the entire world, the whole show. Another possibility suggests itself, that a truthmaker be any minimal sufficer for a proposition. A truthmaker is minimal if it suffices but no proper part of it suffices. A minimal sufficer would be both sufficient for the truth of the proposition and, in one sense, necessary for it as well. A minimal sufficers would be commensurate with the proposition it makes true. Unfortunately not all propositions have minimal sufficers. But it does not follow that not every proposition has a commensurate sufficer. The problem, then, is to specify a coherent notion of commensurateness on which every truth has a commensurate sufficer. I argue that this problem may not be soluble.

Theories of verisimilitude have routinely been classified into two rival camps—the content approach and the likeness approach—and these appear to be motivated by very different sets of data and principles. The question thus naturally arises as to whether these approaches can be fruitfully combined. Recently Zwart and Franssen (Synthese 158(1):75–92, 2007) have offered precise analyses of the content and likeness approaches, and shown that given these analyses any attempt to meld content and likeness orderings violates some basic desiderata. Unfortunately their characterizations of the approaches do not embrace the paradigm examples of those approaches. I offer somewhat different characterizations of these two approaches, as well as of the consequence approach (Schurz and Weingartner (Synthese 172(3):415–436, 2010) which happily embrace their respective paradigms. Finally I prove that the three approaches are indeed compatible, but only just, and that the cost of combining them is too high. Any account which combines the strictures of what I call the strong likeness approach with the demands of either the content or the consequence approach suffers from precisely the same defect as Popper’s—namely, it entails the trivialization of truthlikeness. The downside of eschewing the strong likeness constraints and embracing the content constraints alone is the underdetermination of the concept of truthlikeness