Abstract: Certain prior credence distributions concerning the future lead to inductivism and other distributions lead to inductive skepticism. I argue that it is difficult to see how the latter can be considered reasonable. I do not prove that they are not, but at the end of the paper the tables are turned: in line with pre-philosophical intuitions, inductivism has retaken its position as the most reasonable default position while the skeptic is called on to supply a novel argument for his. The reason is as follows. There are certain possibilities concerning the functioning of the world that, if assigned positive credence, support inductivism. Prima facie, one might think that the alternatives to those possibilities, if assigned similar or more credence, cancel out that support. But, on the contrary, I argue that it is plausible that reasonable credence distributions are such that the alternatives instead cancel themselves out and thus leave the support for inductivism in place.
Keywords: Induction, Bayesianism, Laws of Nature, Grue
Abstract: Inductive reasoning is complicated. According to Bayesianism, it involves assigning prior credences to every conceivable possibility about the future. That's a lot of possibilities. However, useful insights about inductive reasoning and Humean inductive skepticism can be gained by considering simplified models of such reasoning in worlds with fewer possibilities. That is the working hypothesis of this paper.
Keywords: Induction, Bayesian Solution, Nomological-Explanatory Solution
Abstract: The thought experiment of the Presumptious Philosopher was introduced by Bostrom to show that certain theories of anthropic reasoning have obviously unacceptable consequences, namely those theories that imply that an epistemic agent should shift his or her credences towards theories according to which many subjects exist in the history of the universe. By way of historical case studies, this paper attempts to reverse the intuition that this thought experiment has elicited from Bostrom and most other participants in the debate: reasoning “presumptuously” is rational and would have been useful to historical cosmologist. What I defend is approximately the conjunction of the so-called Self-Sampling and Self-Indication Assumptions, but I close the paper by explaining why this conjunction is not entirely correct, and by suggesting an alternative approach to anthropic reasoning.
Keywords: Anthropic Reasoning, History of Cosmology, Bayesianism, The Presumptious Philosopher, The Self-Indication Assumption
Abstract: To determine what the rational credences are for the epistemic agents in the famous cases of self-locating belief, one should model the processes that lead to those agents having the evidence that they have. This is the immensely reasonable approach taken by Darren Bradley (Phil. Review 121, 149-177) and Joseph Halpern (Ergo 2, 195-206). However, they make it seem like this approach must lead to such conclusions as the doomsday argument being correct and that Sleeping Beauty should be a halfer. I argue that this is due to an implicit existential bias: it is assumed that the first step in those processes is the determination that the agent in question must necessarily exist. It is much more reasonable to model that determination as contingent and a result of other, earlier, steps in the process. This paper offers such alternative models. They imply an endorsement of what has mockingly been called “presumptuous” reasoning, and a massive shift of credences in favor of the existence of a multiverse and in favor of the Everettian interpretation of quantum mechanics.
Keywords: Self-Locating Belief, The Doomsday Argument, Sleeping Beauty, Quantum Mechanics, The Fine-Tuning Argument, Protocols, Selection Effects