Anthony S. Gillies

On Truth-Conditions for If (but Not Quite Only If)

For—according to the lore—any attempt at pullingoff this featwill reduce themtomaterial implicationand that is decidedlynot agoodwayof assigning truth-conditions to ordinary indicative if s. That is too bad since it seems like they are bounded from above by strict implication (they are true when their antecedents straight out imply their consequents), are bounded from below by material implication (they are false when their antecedents are true but consequents false), and do go in for the kind of equivalence between (1) and (2).

Belief revision and epistemology

Postulational approaches attempt to understand the dynamics of belief revision by appealing to no more than the set of beliefs held by an agent and the logical relations between them. It is argued there that such an approach cannot work. A proper account of belief revision must also appeal to the arguments supporting beliefs, and recognize that those arguments can be defeasible. If we begin with a mature epistemological theory that accommodates this, it can be seen that the belief revision operators on which the postulational theories are based are ill-defined. It is further argued that there is no way to repair the definitions so as to retain the spirit of those theory. Belief revision is better studied from within an independently motivated epistemological theory.

NEW FOUNDATIONS FOR EPISTEMIC CHANGE

It is no news that there is a debate in epistemology between foundationalists and coherentists. What might be news is that there are two debates, not one. One debate is the familiar one: is the structure of epistemic justification like a pyramid or like a raft? The second debate, which is less well-known to epistemologists, is a debate about the structure of theories of justified or rational belief change. These are, prima facie, quite different debates: the core concept at issue in the first is the concept justified belief (i.e., justification construed as a property of beliefs), whereas in the second what is at issue is the concept justified belief change (i.e., justification construed as a property of transitions between epistemic states). It is this second debate that will concern us here. Foundations theories of belief dynamics take seriously the idea that some beliefs are held on the basis of others – some beliefs (so-called “derived” beliefs) are held “just because” others are.1 Moreover, and more importantly, foundations theories insist that the structure of rational belief change is affected by the fact that some beliefs are held on the basis of others. The main task left for a foundations theory, then, is to give philosophical and formal analyses of the nature of the locution “just because”, and say how it plays a role in how agents ought to revise their picture of the world. Coherence theories deny that any beliefs have or play such a privileged role. The main goal of this paper is to construct some sort of foundations theory of epistemic change. But the foundations theory I ultimately want to construct is a new foundations theory. One sense in which my foundations theory is new is that it affords a new – and entirely semantic – characterization of the derived–non-derived belief distinction. The lesson to be drawn, I think, is that our foundationalist intuitions about belief dynamics are more general than most have thought.

Plausible Deniability and Cooperation in Trust Games

What motivates agents to choose pro-social but dominated actions in principal-agent interactions like the trust game? We investigate this by exploring the role higher-order beliefs about payoffs play in an incentivized laboratory experiment. We find that when there are asymmetries in such higher order information that generates “plausible deniability�?, agents exploit that: otherwise trustworthy types are tempted into defecting.