possibly maybe

 Consider the following propositions: 1. My chair can be three feet to the right of my table. 2. There can be naturally purple cows. 3. There can be an alien substance that plays perfectly the watery role. 4. There can be minds without bodies. 5. There can be an Anselmian being. Does your degree of confidence in the possibility claims listed progressively deflate as you go down the list?  Mine, too. Is your degree of confidence in these claims enhanced by trying to conceive them? Mine, neither. But notice that as we go down the list, the referents of the modal statements progressively decrease in similarity with the actual world and with our knowledge of how the actual world works. Thus, there is a tight correlation between a possibility-candidate’s degree of similarity to the world as we know it, on the one hand, and our degree of confidence in the truth of the candidate’s corresponding modal statement, on the other.  What accounts for this?  I want to suggest what I take to

 1. Concepts 1.1 Primary vs. secondary intensions According to Chalmers’ two-dimensionalism (henceforth 2D), each concept has two components: a primary intension and a secondary intension.   The primary intension of a concept is a function from scenarios to extensions.  Very roughly, a scenario is a comprehensive, consistent hypothesis of a way the actual world could turn out to be that’s not ruled out by what you know a priori.   Thus, consider the hypothesis H that the actual world is one in which everything is the way I believe it to be, except that the stuff that plays the watery role is not H20, but rather XYZ. I can’t rule it out from what I know a priori that H accurately describes the world I live in; H is therefore a scenario.  Now with the notion of a scenario in mind, consider the concept, water.  The primary intension of water is a function from scenarios to extensions, and thus picks out the class of things that, for all I know a priori, can play the watery role (e.g., H20

 Peter Kung offers the most sophisticated version of imagination-based modal epistemology to date. His account is grounded in an account of the nature of sensory imagination that’s informed by recent work on the subject in philosophy and the sciences. The core idea is that sensory imaginings have two kinds of content: qualitative and assigned. Qualitative content consists in mental imagery, which represents a distribution of objects and their qualities in three-dimensional egocentric space.  By contrast, assigned content consists in the labels and descriptions we assign to the objects and properties represented by the sensory content of imagination. According to Kung, the two components of imaginative content differ markedly in terms of the ways in which they can confer justification on a possibility claim. The qualitative content of an imagining can indicate what’s metaphysically possible in virtue of demonstrating a consistent way of “filling in” three-dimensional space.  By contrast

I promise to stop geeking out on early debates in modal epistemology soon and get into contemporary debates, but a current paper I'm working on requires me to do some deep digging into the past. Hence this series: Notes on Geirsson’s “Conceivability and Defeasible Modal Justification”, Phil. Studies , 2005. Geirsson criticizes three of Van Inwagen’s four main arguments for modal skepticism from his paper, " Modal Epistemology ": what he labels as The Analogical Argument , The Different Sources Argument , and The Completeness Argument .  According to The Analogical Argument, our source of modal knowledge is analogous to our source of perceptual knowledge, in the following way: just as our source of perceptual information is a reliable judge of ordinary distances, but an unreliable one when the objects are more remote, so our source of modal information is reliable when its modal judgments are of ordinary matters, but unreliable when they are of matters remote to ordinary l

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In “Modal Epistemology” ( Phil. Studies , 1998), Peter van Inwagen defends a mitigated form of modal skepticism. In particular, he argues that while we have knowledge of many modal claims that are close to the practical concerns of everyday life, science, and even (in some cases) philosophy (e.g., Gettier possibilities), we can’t have knowledge, or even reasonable belief, regarding possibility claims remote from ordinary experience (e.g., the possibility of disembodied souls, Anselmian beings, and instances of gratuitous evil). Van Inwagen further clarifies his version of mitigated modal skepticism by means of an analogy. Just as, in prescientific times, humans confidently formed false perceptual beliefs about distant objects (e.g., the distance of the celestial bodies from the Earth) on the basis of their reliability regarding perceptual judgements about nearby objects, so in the present day philosophers erroneously form confident beliefs about “distant” possibilities on the basis of

Notes on Paul Tidman's “Conceivability as a Test for Possibility”, American Philosophical Quarterly 31(4), October 1994: 297-309. Summary of the paper: Tidman’s paper consists of two main parts: the exposition and critique of conceivability theories of modal epistemology, and a brief exposition of an intuition-based account of modal epistemology.  In the first part, Tidman critiques four main construals of conceivability: conceivability as picturability, as understandability, as believability, and as entertainability. According to the picturability construal, P is conceivable iff one can form a mental image that represents P being the case, where ‘mental image’ is construed broadly enough so as to include the whole gamut of phenomenal imagery: visual images, sounds, tastes, textures, etc. Tidman argues that the picturability account is inadequate for several reasons.  First, many possible states of affairs aren’t picturable, yet we seem to have justified beliefs about the modal st

The publication of Yablo's 1993 PPR paper, "Is Conceivability a Guide to Possibility?" is widely considered a watershed in the history of the epistemology of modality. It's perhaps the most widely cited paper in the subfield to date. And while the subfield has progressed considerably since its publication, it still repays revisiting. And given the blog's aims, I've typed up a fairly careful outline of Yablo's paper. There are still some gaps, so I'll come back in due course to fill them in. 1. Introduction 1.1. Some statements express true propositions about what is metaphysically possible; others do not. 1.2. How can we tell the difference between the two? 1.3. The standard philosophical answer is captured by Hume’s maxim regarding conceivability-possibility inferences:  1.4. Hume’s (modal epistemology) Maxim: “‘Tis an establish'd maxim in metaphysics, that whatever the mind clearly conceives, includes the idea of possible existence, or