My research in epistemology makes sense of knowledge and belief in a probabilistic framework. I like to take anti-skeptical premises — such as that we can know propositions even if they have a non-zero chance of being false — and see what knowledge/belief must look like in light of this (see my dissertation summary for more info). I also work in philosophy language, for instance on belief ascriptions and the semantics of conditionals. See and download my papers below!
A Puzzle about Weak Belief
Belief Revision Revised
Composing Composers
Under Review - comments welcome!
Chancy-but-true Counterfactuals
In preparation; email for draft
Asymmetric Inductive Knowledge
In preparation; email for draft
Weak Belief and Heuristics
In preparation; email for draft
I present an intractable puzzle for currently popular view that belief is weak — the view that expressions like 'S believes p' ascribe to S a doxastic attitude towards p that is rationally compatible with low credence in p. The puzzle concerns issues that arise on considering beliefs in conditionals. I show that proponents of weak belief either cannot consistently apply their preferred methodology when accommodating beliefs in conditionals, or they must deny that beliefs in conditionals can be used in reasoning.
I outline a novel counterexample to the principle of belief revision, Anticipation: if both learning e and learning not-e would render belief in p unjustified, you cannot now be justified in believing p. If I’m right, not only is the leading theory of belief revision false, so are various recently proposed weakenings. I defend a new theory that correctly predicts the failures of Anticipation I argue for, predicated on the simple idea that one is justified in ruling out possibility just in case that possibility is sufficiently improbable.
Suppose you believe on independent grounds that Verdi is Italian, Bizet is French, and Satie is French. To your surprise, you then learn that all three composers are compatriots. What should you believe? Some argue you should be cautious and become ambivalent as to whether all three composers are French or all three are Italian. Surprisingly, if that's right, Composers wreaks epistemological anarchy: a wide variety of epistemological principles turn out to be false. Those resistant to this anarchy instead argue you should be bold and conclude that all three composers are French. I endorse the anarchy. But I do so here in a unique way. Existing approaches to Composers side exclusively with either the cautious or bold reaction, ruling the other out as irrational. This is undesirable: both judgements look reasonable. I outline a new approach to Composers that successively captures this permissive element of the case.
Were I to throw my keyboard, it would hit the wall. Yet according to our best scientific theories there is a non-zero chance it would quantum-tunnel through the wall. This is puzzling: how can we say my keyboard would hit the wall, if it might quantum-tunnel through it? ‘Counterfactual Lockeanism’ attempts reconciliation by claiming that the counterfactual A>C is true just in case the objective chance of C conditional on A is non-maximally high. Philosophers have found this view implausible — for instance, it implies the absurd conclusion that both A>C1 and A>C2 can be true even if A>C1&C2 is false. Philosophers have therefore tended towards views on which the truth of A>C is severed from the chance of C given A, such that A>C can be true even if C is extremely unlikely given A. I argue this severance has been accepted too quickly. We can construct a theory on which the truth of A>C is significantly constrained by the chance of C given A that nevertheless avoids the pitfalls of Counterfactual Lockeanism.
Consider Alice, who is unsure whether the urn in front of her is ‘Uniform’ and contains 1,000 marbles, or is ‘Mixed’ and contains 500 green and 500 blue marbles. She randomly samples 100 marbles, sees that they are all green, and believes on this basis that the urn is Uniform. Anti-skeptics should concede that in at least some version of this case, Alice’s belief can constitute knowledge. I argue that this anti-skeptical position is only tenable if we maintain that Alice’s knowledge is asymmetric in various surprising ways. One such striking asymmetry implies a kind of ego-centrism; for instance, I argue that while Alice can know before looking at her sample that if all the marbles in her sample are green, the urn is Uniform, she is, surprisingly, not able to know of some other equally-sized random sample S that if all the marbles in S are green, the urn is Uniform. This raises a puzzle: can any plausible theory of knowledge accommodate such bizarre asymmetries? I outline a theory that can.
The idea that there is a weak sense of 'belief' — by which belief in p is rational compatible with low credence that p — is becoming increasingly popular. At the same time, this idea has generated various puzzles, including those given by myself, Helena Fang, and Richard Teague. Here, I argue these puzzles all arise from the same source, and so have a unified solution. The key is to realize that weak beliefs are rationally formed using heuristics. It is well known that applying multiple good heuristics to the same problem can lead to inconsistent results. These puzzles merely demonstrate is how this familiar phenomenon occurs in the context of weak belief.
Joshua Edward Pearson
