I am an Assistant Professor in the Department of Philosophy at Bilkent University.  I work mainly in metaphysics, epistemology, and philosophy of probability.

The overarching aim of my research is to develop a probabilistic epistemology for metaphysicsthat is, a systematic epistemology for determining how confident we ought to be in propositions of metaphysical interest.  I am currently developing a probabilistic approach to metaphysics that is centered around the idea of epistemic modesty and applying it to develop a novel argument against external-world skepticism and to address the question of whether simplicity is a guide to truth.  I am also interested in a number of independent topics in philosophy of probability, including qualitative probability, principles of indifference, and the relation between probability and infinity.

I received my B.S. in Physics from MIT in 2009 and my PhD in Philosophy from Stanford University in 2018.

I can be reached at dibella [at] bilkent [dot] edu [dot] tr.

Below are some of my papers.  Comments are very welcome!
  • "The Qualitative Paradox of Non-Conglomerability"
    2018.  Synthese, 195(3), 1181-1210.
    Abstract.  A probability function is non-conglomerable just in case there is some proposition E and partition π of the space of possibilities such that the probability of E conditional on any member of π is bounded by two values yet the unconditional probability of E is not bounded by those values.  The paradox of non-conglomerability is the counterintuitive—and controversial—claim that a rational agent's subjective probability function can be non-conglomerable.  In this paper, I present a qualitative analogue of the paradox.  I show that, under antecedently plausible assumptions, an analogue of the paradox arises for rational comparative confidence.  As I show, the qualitative paradox raises its own distinctive set of philosophical issues.

  • "Probabilistic Proof of an External World"
    Abstract.  (Draft.)  I provide a novel internal critique of skepticism about the external world.  Appealing to premises that an external-world skeptic could accept, I argue that the skeptic should (by her own lights) be extraordinarily confident that an external world exists.  These premises include commitments to various forms of a priori reasoningincluding commitments to classical logic, set theory, and probabilistic reasoningas well as radical empiricism about evidence.  As I argue, these premises entail that the skeptic should, by her own lights, be at least 99.99999% confidentjust shy of certainthat an external world exists.
  • "The Infinitesimal Significance of Infinitesimals"
    Abstract.  (Draft.)  Infinitesimal probability has long enjoyed a prominent role in the philosophy of probability.  It has been employed for such purposes as defending the principle of regularity, making sense of rational belief update upon learning evidence of classical probability 0, modeling fair infinite lotteries, and applying decision theory in infinitary contexts.  In this paper, I provide a theory of qualitative probabilitywhich I call Qualitative Probability Theory (QP)that can serve all of these purposes and more.  Additionally, I argue that QP can serve these purposes more simply, more perspicuously, and with less cost than theories of infinitesimal probability.  Finally, I argue that QP has comparable (if not greater) representational power than the theory of infinitesimal probability recently developed by Benci et al. (2013, 2016)Non-Archimedean Probability Theory (NAP).  These considerations suggest that qualitative probability provides a superior framework to infinitesimal probability for theorizing about infinitary probabilistic scenarios that have philosophical significance.

  • "The World Is (Almost Surely) a Strange Place"
    Abstract.  (Draft.)  I argue that we should be extremely confident that the world is extraordinarily ontologically complex.  More precisely, I argue for the following thesis: for any (finite or infinite) cardinality K, we should at least 99.99999% confident that there exist more than K-many things in total as well as more than K-many kinds of things.  This thesis contrasts starkly with the widespread view in science and metaphysics that simplicity is a guide to truth.
Please email me for drafts of the following papers:
  • "Indifference Defended"
    Abstract.  I defend the Principle of Indifference (POI) in light of the popular objection that it is inconsistent.  In particular, I argue that in those cases in which POI allegedly leads to contradiction, POI can only be appropriately applied (if at all) at the level of epistemically possible worlds.  As I argue, when POI is applied at this level, the allegedly damning contradictions no longer arise.
My CV can be found here.