Updating for Externalists

The externalist says that your evidence could fail to tell you what evidence you do or not do have. In that case, it could be rational for you to be uncertain about what your evidence is. This is a kind of uncertainty which orthodox Bayesian epistemology has difficulty modeling. For, if externalism is correct, then the orthodox Bayesian learning norms of conditionalization and reflection are inconsistent with each other. I recommend that an externalist Bayesian reject conditionalization. In its stead, I provide a new theory of rational learning for the externalist. I defend this theory by arguing that its advice will be followed by anyone whose learning dispositions maximize expected accuracy. I then explore some of this theory’s consequences for the rationality of epistemic akrasia, peer disagreement, undercutting defeat, and uncertain evidence

Cognitive Mobile Homes

While recent discussions of contextualism have mostly focused on other issues, some influential early statements of the view emphasized the possibility of its providing an alternative to both coherentism and traditional versions of foundationalism. In this essay, I will pick up on this strand of contextualist thought, and argue that contextualist versions of foundationalism promise to solve some problems that their non-contextualist cousins cannot. In particular, I will argue that adopting contextualist versions of foundationalism can let us reconcile Bayesian accounts of belief updating with a version of the holist claim that all beliefs are defeasible

How to Learn from Theory-Dependent Evidence; or Commutativity and Holism: A Solution for Conditionalizers

Weisberg ([2009]) provides an argument that neither conditionalization nor Jeffrey conditionalization is capable of accommodating the holist’s claim that beliefs acquired directly from experience can suffer undercutting defeat. I diagnose this failure as stemming from the fact that neither conditionalization nor Jeffrey conditionalization give any advice about how to rationally respond to theory-dependent evidence, and I propose a novel updating procedure that does tell us how to respond to evidence like this. This holistic updating rule yields conditionalization as a special case in which our evidence is entirely theory independent

The structure of perceptual justification

When does a perceptual experience as of my hands provide justification for me to believe that I have hands? One initially plausible positive requirement is that I must have reasons to believe something else: that my experience is veridical. Also plausible is the negative requirement that I must not have reasons to believe that my experience is in this case non-veridical. Dogmatists about perception reject the positive requirement and embrace the negative one, holding that perceptual justification is immediate — it doesn’t rest upon any other justification that I possess — but it is also defeasible, and in particular it is underminable. Whereas Dogmatism is a theory in the epistemology of perception, Bayesianism is a theory of coherence for partial beliefs and of how coherence it to be maintained in the face of new evidence. Just as it is incoherent to believe both I have hands and ¬(I have hands), it is incoherent to be highly confident in both of those propositions. Bayesianism offers a formal account of this latter type of coherence. Importantly, though Bayesianism is a theory of coherence, it is not a coherence theory of the sort defended by Davidson and BonJour: it is not an attempt to explain all facts about justification in terms of facts about coherence. Hence the Bayesian’s claim that partial beliefs are subject to norms of coherence is at least prima facie consistent with the Dogmatist’s claim that some beliefs are immediately justified by experience. I develop and defend Bayesian Dogmatism. I begin by responding to an argument advanced by Cohen, Hawthorne, Schiffer, and White, which purports to show that Bayesians cannot model episodes of perceptual learning in which the proposition learned is both immediately justified and defeasible. I go on to respond to arguments from Weisberg, which purport to show that Bayesianism is inconsistent with underminable perceptual learning. Finally, I defend the superiority of Jeffrey Conditionalization to Holistic Conditionalization as a rule of updating on propositions learned from experience.Philosoph

Is conditioning really incompatible with holism?

Jonathan Weisberg (British J. for the Phil. of Science 60(2009), 793-812) claims, that in an interesting class of cases, probability assessments constructed by strict or Jeffrey conditioning preclude subsequent revision by after-the-fact defeaters of the reasons supporting those assessments, and that conditioning is thus "inherently anti-holistic." His analysis founders, however, in applying Jeffrey conditioning to a partition for which an essential rigidity condition clearly fails. Applied to an appropriate partition, Jeffrey conditioning is amenable to revision by after-the-fact defeaters in precisely the way that Weisberg demands

Homeostatic epistemology : reliability, coherence and coordination in a Bayesian virtue epistemology

How do agents with limited cognitive capacities flourish in informationally impoverished or unexpected circumstances? Aristotle argued that human flourishing emerged from knowing about the world and our place within it. If he is right, then the virtuous processes that produce knowledge, best explain flourishing. Influenced by Aristotle, virtue epistemology defends an analysis of knowledge where beliefs are evaluated for their truth and the intellectual virtue or competences relied on in their creation. However, human flourishing may emerge from how degrees of ignorance are managed in an uncertain world. Perhaps decision-making in the shadow of knowledge best explains human wellbeing—a Bayesian approach? In this dissertation I argue that a hybrid of virtue and Bayesian epistemologies explains human flourishing—what I term homeostatic epistemology. \ud \ud Homeostatic epistemology supposes that an agent has a rational credence p when p is the product of reliable processes aligned with the norms of probability theory; whereas an agent knows that p when a rational credence p is the product of reliable processes such that: 1) p meets some relevant threshold for belief (such that the agent acts as though p were true and indeed p is true), 2) p coheres with a satisficing set of relevant beliefs and, 3) the relevant set of beliefs is coordinated appropriately to meet the integrated aims of the agent. \ud \ud Homeostatic epistemology recognizes that justificatory relationships between beliefs are constantly changing to combat uncertainties and to take advantage of predictable circumstances. Contrary to holism, justification is built up and broken down across limited sets like the anabolic and catabolic processes that maintain homeostasis in the cells, organs and systems of the body. It is the coordination of choristic sets of reliably produced beliefs that create the greatest flourishing given the limitations inherent in the situated agent. \u