•  1717
    I Ought, Therefore I Can
    Philosophical Studies 136 (2): 167-216. 2007.
    I defend the following version of the ought-implies-can principle: (OIC) by virtue of conceptual necessity, an agent at a given time has an (objective, pro tanto) obligation to do only what the agent at that time has the ability and opportunity to do. In short, obligations correspond to ability plus opportunity. My argument has three premises: (1) obligations correspond to reasons for action; (2) reasons for action correspond to potential actions; (3) potential actions correspond to ability plus…Read more
  •  1445
    You may not know me well enough to evaluate me in terms of my moral character, but I take it you believe I can be evaluated: it sounds strange to say that I am indeterminate, neither good nor bad nor intermediate. Yet I argue that the claim that most people are indeterminate is the conclusion of a sound argument—the indeterminacy paradox—with two premises: (1) most people are fragmented (they would behave deplorably in many and admirably in many other situations); (2) fragmentation entails indet…Read more
  •  1211
    Epsilon-ergodicity and the success of equilibrium statistical mechanics
    Philosophy of Science 65 (4): 688-708. 1998.
    Why does classical equilibrium statistical mechanics work? Malament and Zabell (1980) noticed that, for ergodic dynamical systems, the unique absolutely continuous invariant probability measure is the microcanonical. Earman and Rédei (1996) replied that systems of interest are very probably not ergodic, so that absolutely continuous invariant probability measures very distant from the microcanonical exist. In response I define the generalized properties of epsilon-ergodicity and epsilon-continui…Read more
  •  1187
    Hempel's Raven paradox: A lacuna in the standard bayesian solution
    British Journal for the Philosophy of Science 55 (3): 545-560. 2004.
    According to Hempel's paradox, evidence (E) that an object is a nonblack nonraven confirms the hypothesis (H) that every raven is black. According to the standard Bayesian solution, E does confirm H but only to a minute degree. This solution relies on the almost never explicitly defended assumption that the probability of H should not be affected by evidence that an object is nonblack. I argue that this assumption is implausible, and I propose a way out for Bayesians. Introduction Hempel's parad…Read more
  •  1149
    Can I kill my younger self? Time travel and the retrosuicide paradox
    Pacific Philosophical Quarterly 90 (4): 520-534. 2009.
    If time travel is possible, presumably so is my shooting my younger self ; then apparently I can kill him – I can commit retrosuicide. But if I were to kill him I would not exist to shoot him, so how can I kill him? The standard solution to this paradox understands ability as compossibility with the relevant facts and points to an equivocation about which facts are relevant: my killing YS is compossible with his proximity but not with his survival, so I can kill him if facts like his survival ar…Read more
  •  1046
    The first sentence of NE I.2 has roughly the form: "If A [there is a universal end] and B, then D [this end will be the best good]". According to some commentators, Aristotle uses B to infer A; but then the sentence is fallacious. According to other commentators, Aristotle does not use B ; but then the sentence is bizarre. Contrary to both sets of commentators, I suggest that Aristotle uses B together with A to infer validly that there is a non-instrumental – and thus unique – universal end. On …Read more
  •  1017
    Imperatives cannot be true or false, so they are shunned by logicians. And yet imperatives can be combined by logical connectives: "kiss me and hug me" is the conjunction of "kiss me" with "hug me". This example may suggest that declarative and imperative logic are isomorphic: just as the conjunction of two declaratives is true exactly if both conjuncts are true, the conjunction of two imperatives is satisfied exactly if both conjuncts are satisfied—what more is there to say? Much more, I argue.…Read more
  •  983
    Do Cry Over Spilt Milk
    The Monist 88 (3): 370-387. 2005.
    There is widespread agreement, even among those who accept the possibility of backward causation, that it is impossible to change the past. I argue that this agreement corresponds to a relatively uninteresting understanding of what changing the past amounts to. In one sense it is indeed impossible to change the past: in no possible world is an action performed which makes the past in that world different from the past in that world. In another sense, however, it may be possible to change the pas…Read more
  •  922
    What time travelers may be able to do
    Philosophical Studies 150 (1). 2010.
    Kadri Vihvelin, in "What time travelers cannot do" (Philos Stud 81: 315-330, 1996), argued that "no time traveler can kill the baby who in fact is her younger self, because (V1) "if someone would fail to do something, no matter how hard or how many times she tried, then she cannot do it", and (V2) if a time traveler tried to kill her baby self, she would always fail. Theodore Sider (Philos Stud 110: 115-138, 2002) criticized Vihvelin's argument, and Ira Kiourti (Philos Stud 139: 343-352, 2008) c…Read more
  •  748
    In Defense of Imperative Inference
    Journal of Philosophical Logic 39 (1). 2010.
    "Surrender; therefore, surrender or fight" is apparently an argument corresponding to an inference from an imperative to an imperative. Several philosophers, however (Williams 1963; Wedeking 1970; Harrison 1991; Hansen 2008), have denied that imperative inferences exist, arguing that (1) no such inferences occur in everyday life, (2) imperatives cannot be premises or conclusions of inferences because it makes no sense to say, for example, "since surrender" or "it follows that surrender or fight"…Read more
  •  685
    Who's afraid of undermining?
    Erkenntnis 57 (2): 151-174. 2002.
    The Principal Principle (PP) says that, for any proposition A, given any admissible evidence and the proposition that the chance of A is x%, one's conditional credence in A should be x%. Humean Supervenience (HS) claims that, among possible worlds like ours, no two differ without differing in the spacetime-point-by-spacetime-point arrangement of local properties. David Lewis (1986b, 1994a) has argued that PP contradicts HS, and the validity of his argument has been endorsed by Bigelow et al. (19…Read more
  •  657
    I defend the epistemic thesis that evaluations of people in terms of their moral character as good, bad, or intermediate are almost always epistemically unjustified. (1) Because most people are fragmented (they would behave deplorably in many and admirably in many other situations), one's prior probability that any given person is fragmented should be high. (2) Because one's information about specific people does not reliably distinguish those who are fragmented from those who are not, one's pos…Read more
  •  536
    Imperatives, Logic Of
    In Hugh LaFollette (ed.), The International Encyclopedia of Ethics, Blackwell. pp. 2575-2585. 2013.
    Suppose that a sign at the entrance of a hotel reads: “Don’t enter these premises unless you are accompanied by a registered guest”. You see someone who is about to enter, and you tell her: “Don’t enter these premises if you are an unaccompanied registered guest”. She asks why, and you reply: “It follows from what the sign says”. It seems that you made a valid inference from an imperative premise to an imperative conclusion. But it also seems that imperatives cannot be true or false, so what doe…Read more
  •  526
    Have your cake and eat it too: The old principal principle reconciled with the new
    Philosophy and Phenomenological Research 69 (2). 2004.
    David Lewis (1980) proposed the Principal Principle (PP) and a “reformulation” which later on he called ‘OP’ (Old Principle). Reacting to his belief that these principles run into trouble, Lewis (1994) concluded that they should be replaced with the New Principle (NP). This conclusion left Lewis uneasy, because he thought that an inverse form of NP is “quite messy”, whereas an inverse form of OP, namely the simple and intuitive PP, is “the key to our concept of chance”. I argue that, even if OP …Read more
  •  524
    Respect for Persons: An Epistemic and Pragmatic Investigation
    Dissertation, University of Michigan. 2001.
    We can distinguish two concepts of respect for persons: appraisal respect , an attitude based on a positive appraisal of a person's moral character, and recognition respect , the practice of treating persons with consideration based on the belief that they deserve such treatment. After engaging in an extended analysis of these concepts, I examine two "truisms" about them. We justifiably believe of some persons that they have good character and thus deserve our esteem . Frequently it pays to be d…Read more
  •  508
    Imperatives cannot be true, but they can be obeyed or binding: `Surrender!' is obeyed if you surrender and is binding if you have a reason to surrender. A pure declarative argument — whose premisses and conclusion are declaratives — is valid exactly if, necessarily, its conclusion is true if the conjunction of its premisses is true; similarly, I suggest, a pure imperative argument — whose premisses and conclusion are imperatives — is obedience-valid (alternatively: bindingness-valid) exactly if,…Read more
  •  335
    I was quite excited when I first read Restall and Russell’s (2010) paper. For two reasons. First, because the paper provides rigorous formulations and formal proofs of implication barrier the- ses, namely “theses [which] deny that one can derive sentences of one type from sentences of another”. Second (and primarily), because the paper proves a general theorem, the Barrier Con- struction Theorem, which unifies implication barrier theses concerning four topics: generality, necessity, time, and no…Read more
  •  238
    [1] You have a crystal ball. Unfortunately, it’s defective. Rather than predicting the future, it gives you the chances of future events. Is it then of any use? It certainly seems so. You may not know for sure whether the stock market will crash next week; but if you know for sure that it has an 80% chance of crashing, then you should be 80% confident that it will—and you should plan accordingly. More generally, given that the chance of a proposition A is x%, your conditional credence in A shoul…Read more
  •  199
    I Ought, Therefore I Can Obey
    Philosophers' Imprint 18. 2018.
    According to typical ought-implies-can principles, if you have an obligation to vaccinate me tomorrow, then you can vaccinate me tomorrow. Such principles are uninformative about conditional obligations: what if you only have an obligation to vaccinate me tomorrow if you synthesize a vaccine today? Then maybe you cannot vaccinate me tomorrow ; what you can do instead, I propose, is make it the case that the conditional obligation is not violated. More generally, I propose the ought-implies-can-o…Read more
  •  141
    I was quite excited when I first read Restall and Russell’s (2010) paper. For two reasons. First, because the paper provides rigorous formulations and formal proofs of implication barrier theses, namely “theses [which] deny that one can derive sentences of one type from sentences of another”. Second (and primarily), because the paper proves a general theorem, the Barrier Construction Theorem, which unifies implication barrier theses concerning four topics: generality, necessity, time, and normat…Read more
  •  133
    Lack of Character: Personality and Moral Behavior (review)
    Philosophical Review 113 (2): 284-288. 2004.
    I agree with all four of the above theses, but I will argue that some of Doris’s arguments need improvement. I will deal only with arguments in defense of the thesis that situationism is true.
  •  125
    Sep 17 Time travel in Special Relativity (1) Nahin 1999: 439-51 & 459-66; (2) Taylor & Wheeler 1992: 121-35; (3) Nahin 1999: 343-8. Sep 24 Time travel in General Relativity (1) Malament 1985: 91-5; (2) Thorne 1994: 483-90 & 498-521; (3) Gott 2001: 92-110. Oct 1 Time travel in Quantum Mechanics (1) Albert 1992: 17-38, 73-9, & 112-5; (2) Barrett 1999: 149-62; (3) Deutsch & Lockwood 1994.
  •  116
    Besides pure declarative arguments, whose premises and conclusions are declaratives (“you sinned shamelessly; so you sinned”), and pure imperative arguments, whose premises and conclusions are imperatives (“repent quickly; so repent”), there are mixed-premise arguments, whose premises include both imperatives and declaratives (“if you sinned, repent; you sinned; so repent”), and cross-species arguments, whose premises are declaratives and whose conclusions are imperatives (“you must repent; so r…Read more
  •  115
    The claim that (OIC) “ought” implies “can” (i.e., you have an obligation only at times at which you can obey it) entails that (1) obligations that become infeasible are lost (i.e., you stop having an obligation when you become unable to obey it). Moreover, the claim that (2) obligations that become overridden are not always lost (i.e., sometimes you keep having an obligation when you acquire a stronger incompatible obligation) entails that (ONIM) “ought” does not imply “must” (i.e., some obligat…Read more
  •  72
    I outline six components of a comprehensive proposal for overhauling the foundations of deontic logic. (1) Actions and prescriptions are temporally indexed; more precisely, they attach to nodes of a tree in a branching time structure. (2) Actions are (modeled as) sets of branches and can be coarse- or fine-grained depending on whether or not they have proper subsets which are also actions. (3) Prescriptions have satisfaction and violation sets; these are sets of branches which may—but need not—b…Read more
  •  69
    Informative Aboutness
    Australasian Journal of Philosophy 95 (2): 354-364. 2017.
    Pretheoretically, ‘all believers are immortal’ is about all believers, but B is not about any unbeliever. Similarly, ‘all mortals are unbelievers’ is not about any immortal, but M is about all mortals. But B and M are logically equivalent universal generalizations, so arguably they are about exactly the same objects; by, they are about those mortals who are unbelievers, contradicting. If one responds by giving up, is there still a sense in which B treats unbelievers differently from believers? I…Read more