I lay out the framework for my theory of sensory imagination in “Imagining as a guide to possibility.” Sensory imagining involves mental imagery, and crucially, in describing the content of imagining, I distinguish between qualitative content and assigned content. Qualitative content derives from the mental image itself; for visual imaginings, it is what is “pictured.” For example, visually imagine the Philadelphia Eagles defeating the Pittsburgh Steelers to win their first Super Bowl. You picture the greenness of the field and the football’s brown oblong shape. Some of what you imagine isn’t explicitly pictured, however. That it is Sunday, that it is the Super Bowl: these facts are assigned.

An upshot of my theory of imagination and modal epistemology is that, contra authors like Saul Kripke and Stephen Yablo, we quite frequently imagine the impossible. Kripke and Yablo take modal considerations to show that we cannot be imagining what we think we imagine. In effect these authors espouse an error theory of imagination: because, e.g., it is impossible for Hesperus not to be Phosphorus, then despite what we might think, we cannot imagine Hesperus without Phosphorus. In “You really do imagine it: Against error theories of imagination,” I argue that this is a mistake. It is quite straightforward to imagine impossible situations via assignment; in slogan form, “assignment makes imagining the impossible possible.” For example, we can imagine two distinct heavenly bodies and assign one to be Hesperus and the other to be Phosphorus. This is as routine as assigning that the imagined football game is the Super Bowl.

Given my modal epistemology, our ability to imagine the impossible needn’t commit us to eschewing imagination as a source of modal evidence. In our example, the fact that the identities of Hesperus and Phosphorus were assigned shows that the imagining provides no evidence that Hesperus could be distinct from Phosphorus. I analyze a number of other familiar cases in the conceivability/possibility literature — a posteriori necessities, proving/disproving Goldbach’s conjecture, necessity of origins, past-changing time travel, and so on — and show that in each case, reliance on assignments permits us to imagine the impossible. Hence by my lights these imaginings provide no evidence for possibility.

Many thought experiments in philosophy of mind, in particular the famous modal arguments for dualism, rely on imagining from the first-person perspective. I explain the difference between imagining from the first- vs. third-person perspective in “Imagining, inside and out.” In fictional writing we distinguish the author of a story, the story itself, and how the story is told. The same author can tell the same story in a first-person or a third-person narrative; the story will be the same in that it has the same characters undertaking the same actions in pursuit of the same goals. For example, compare Twain writing, “I took the canoe out from the shore a little piece,” where Huck narrates, vs. “Huck took the canoe out from the shore a little piece.”

I argue that imagining from the first-person perspective, or from the inside, features a character in the story from whose perspective the narrative unfolds, whereas in imagining from the outside, there is no such character. I dub this character “Ego.” I caution that we should not conflate the character Ego with the author Peter Kung. We assign Ego an identity (in my sense of ‘assign’ from above). Ego does not have to be Peter Kung in every story. Sometimes I assign Ego to be Peter Kung; other times, when I imagine being someone else, I assign Ego to be someone other than Peter Kung, say Tiger Woods.

I show how properly understanding imagining from the inside allows a satisfying analysis of famous dualist zombie and disembodiment thought experiments. We imagine our zombie twin from the outside (contra Thomas Nagel and Sydney Shoemaker), assigning both that the creature is a microphysical duplicate of us and that it is nonconscious. Hence imagining a zombie fails to provide evidence that zombies are possible. We imagine being disembodied from the inside; when I do it, I need to assign that Ego is Peter Kung. Therefore while imagining might provide evidence that some subject could be disembodied, it generates no evidence that Peter Kung could be disembodied. Hence these thought experiments offer at best only limited support for dualism.

In these two papers I examine radical skepticism. Many skeptical arguments are driven by skeptical thought experiments: imagine that you are dreaming, a brain in a vat, or the victim of a demon deceiver. I believe that the most radial skeptical thought experiments fail to raise legitimate skeptical doubt. The argument proceeds in two steps.

The first step examines what features a skeptical scenario has to have to raise legitimate doubt. I argue in “What makes a good skeptical thought experiment?” that a number of the leading candidates in the skepticism literature are inadequate. Take, for example, logical possibility: does a skeptical scenario’s logical possibility suffice to raise doubt about our external world beliefs? I argue no. If we could rule out skeptical scenarios using logic alone, that would put our perceptual knowledge on a reassuringly firm logical foundation. But unless we are given some reason to think that we should be able to establish the falsity of a skeptical scenario using logic alone, that there is some reason to privilege logic here, the mere logical possibility of a skeptical scenario has no skeptical force. I conclude that only a skeptical scenario’s metaphysical possibility has any hope of raising skeptical doubt.

I then turn, in the second step “On the possibility of skeptical scenarios,” to whether we are justified in believing that radical skeptical scenarios are metaphysically possible. I argue using my modal epistemological framework above that if we are, that justification rests on our having antecedent justification for believing things about the external world. For example, imagining being a BIV requires that we assign all sorts of facts: that brains are the causal basis for consciousness, that computers can artificially stimulate nerve centers, and so on. Because these facts are assigned, imagining them provides no evidence that such facts are possible; if we have such evidence, it must come from our justification for thinking that those facts are actual. In other words, skeptical arguments based on radical skeptical thought experiments like the BIV scenario presuppose justified beliefs about the external world. This dependence, I claim, undermines the potency of radical skeptical thought experiments.

Several authors have mounted Bayesian objections to modest foundationalism. Several versions of modest foundationalism contend that perceptual experience justifies belief provided you have no reason to believe that your experience misleads. Objectors treat having no reason no differently than having balanced evidence for and against. They argue that the Bayesian principle of evidential confirmation — evidence E confirms hypothesis H just in case Pr(H|E)>Pr(H) — proves that contra modest foundationalism, perceptual experience cannot justify belief in the absence of antecedence justification for believing that perception is reliable.

I use Keynes’ and Knight’s distinction between risk and uncertainty to argue in "On having no reason" that the Bayesian principle fails to accommodate the intuitive notion of having no reason to believe. Consider as an example an unfamiliar card game: at first, since you’re unfamiliar with the game, you assign credences based on the indifference principle. Later you learn how the game works and discover that the odds dictate you assign the very same credences. Examples like this show that that if you initially have no reason to believe H, then intuitively E can give you reason to believe H even though Pr(H|E)<=Pr(H). I show that without the principle, the objections to modest foundationalism fail.

I co-authored these two papers with Masahiro Yamada of Claremont Graduate University. In them we take on the problem of easy knowledge, due to Jonathan Vogel and Stewart Cohen, that has garnered a lot of attention in the epistemology literature recently.

The problem of easy knowledge objects to modest foundationalism on the grounds that it makes it absurdly easy to generate justification to believe that one’s perceptual faculties are reliable. We agree that the problem of easy knowledge is a problem, but contend the problem has nothing to do with modest foundationalism. Understanding the real problem requires a better understanding of different ways that arguments can beg the question.

In “A neglected way of begging the question,” we argue that not all question-begging arguments are circular. We offer two examples. Our diagnosis is that a procedure can presuppose a conclusion just as a premise-circular argument can presuppose the conclusion as a premise; this happens when a procedure is rigged in advance to give only one conclusion.

We make this notion of rigging more precise in “There is no easy bootstrapping problem.” The idea, roughly, is that if it ought to be obvious to you, just by inspecting your procedure, that it cannot recognize counterexamples to a universal generalization even if there are some, then using that procedure generates no inductive support for the universal generalization. We argue that everyone needs to acknowledge that rigged procedures are epistemically problematic. Since excluding rigged procedures solves the bootstrapping problem, we conclude that bootstrapping poses no special problem for modest foundationalism.