I develop and defend a sense-datum theory of perception. My theory follows the spirit of classic sense-datum theories: I argue that what it is to have a perceptual experience is to be acquainted with some sense-data, where sense-data are private particulars that have all the properties they appear to have, that are common to both perception and hallucination, that constitute the phenomenal characters of perceptual experiences, and that may be aptly described as pictures inside one’s head. But my theory also diverges from conventional sense-datum theories in some key respects: on my view, (1) sense-data are neural states presented first-personally, (2) the sensational qualities of sense-data differ in kind from the sensible qualities of external objects, and (3) sense-data are the vehicles in virtue of which we perceive, rather than the objects that we perceive. I argue that this package of claims is appropriately labeled ‘sense-datum theory’, and that the resultant view ought to be a live contender in contemporary philosophy of perception.

What is the temporal structure of conscious experience? While it is popular to think that our most basic conscious experiences are temporally extended, we will be arguing against this view, on the grounds that it makes our conscious experiences depend on the future in an implausible way. We then defend an alternative view of the temporal structure of experience from a variety of different objections. Along the way, we hope to illustrate the wider philosophical ramifications of the relationship between experience and time. What one thinks about the temporal structure of experience is, we believe, deeply interconnected with issues concerning whether consciousness is vague or precise, whether conscious states can be reduced to physical states, whether phenomenal properties are intrinsic properties, and whether phenomenal consciousness can “overflow” access consciousness. As we will see, even seemingly unrelated metaphysical questions, such as the debate between Humean and Non-Humean accounts of natural necessity, bear on questions about the relationship between experience and time.

Some physical theories predict that almost all brains in the universe are Boltzmann brains, i.e. short-lived disembodied brains that are accidentally assembled as a result of thermodynamic or quantum fluctuations.  Physicists and philosophers of physics widely regard this proliferation as unacceptable, and so take its prediction as a basis for rejecting these theories.  But the putatively unacceptable consequences of this prediction follow only given certain philosophical assumptions.  This paper develops a strategy for shielding physical theorizing from the threat of Boltzmann brains.  The strategy appeals to a form of phenomenal externalism about the physical basis of consciousness. Given that form of phenomenal externalism, the proliferation of Boltzmann brains turns out to be benign. While the strategy faces a psychophysical fine-tuning problem, it both alleviates cosmological fine-tuning concerns that attend physics-based solutions to Boltzmann brain problems and pays explanatory dividends in connection with time’s arrow.

Consider the totality of your phenomenal experience right now — your total experience. Is there a total experience which is phenomenally different from yours, but which differs only by a mirror symmetry, the way that a picture of a left hand differs from a picture of right hand, or is there no phenomenal difference between a total experience and its mirror-reversal? If you think that there is a phenomenal distinction between an experience and its mirror reversal (a position Chalmers dubs `e-categoricalism’) then you may find it intuitive that your mirror twin — someone who is a molecule-for-molecule mirror reflection of you — in general has a different experience than you. After all, if you are looking at your left hand, she is looking at her right hand. Lee (2006) argues, however, that your mirror twin must be your phenomenal twin, if relationalism about space is correct. Paired with e-categorialism this has puzzling consequences. Here, I begin by challenging Lee. I argue that even given relationalism about space, your mirror twin can fail to be your phenomenal twin. But this result is limited. It only applies where you and your mirror twin both live in a universe with an orientable topology. If your universe has a non-orientable topology (in the sense in which Möbius strips and Klein bottles have non-orientable topologies) then your mirror twin must be your phenomenal twin after all. Moreover, this moral applies even to those who reject relationalism about space. The upshot is that everyone, non-relationalists included, must either abandon e-categoricalism, or choose between puzzling consequences along the lines Lee outlines, the most promising of which may be property dualism.

We argue that intentions are beliefs—beliefs that are held in light of, and made rational by, practical reasoning. To intend to do something is neither more nor less than to believe, on the basis of one’s practical reasoning, that one will do it. The identification of the mental state of intention with the mental state of belief is what we call strong cognitivism about intentions.

There has been a lot of discussion about whether a subject has a special sort of access to her own mental states, different in important ways from her access to the states of others. But assuming that subjects can genuinely find out about their own minds, is the kind of import of acquiring self-knowledge different in some interesting, principled way from the import of finding out about the mental states of others? Consider, in particular, the import of finding out about the doxastic states of others who share your evidence. It has been a very popular view of late that evidence about the opinions of others can provide both evidence about one’s evidence, and evidence about first-order matters that the evidence bears on. So, for instance, learning that a friend who shares my evidence is very confident that p can give me evidence that my evidence supports p, and evidence that p is true. But assuming that my own states are not perfectly luminous to me, could learning what I think about a matter have the same kind of evidential import? For instance, could learning that I am confident that p give me more evidence about whether p? It is very tempting to think that evidence about my own doxastic states is inert in a way that evidence about the states of others is not. I argue that this is wrong: there is no principled difference between the evidential import of these two kinds of evidence. Asking what I think about a matter can be a perfectly legitimate way of gaining more evidence about it.

There has been a lot of discussion about whether a subject has a special sort of access to her own mental states, different in important ways from her access to the states of others. But assuming that subjects can genuinely find out about their own minds, is the kind of import of acquiring self-knowledge different in some interesting, principled way from the import of finding out about the mental states of others? Consider, in particular, the import of finding out about the doxastic states of others who share your evidence. It has been a very popular view of late that evidence about the opinions of others can provide both evidence about one’s evidence, and evidence about first-order matters that the evidence bears on. So, for instance, learning that a friend who shares my evidence is very confident that p can give me evidence that my evidence supports p, and evidence that p is true. But assuming that my own states are not perfectly luminous to me, could learning what I think about a matter have the same kind of evidential import? For instance, could learning that I am confident that p give me more evidence about whether p? It is very tempting to think that evidence about my own doxastic states is inert in a way that evidence about the states of others is not. I argue that this is wrong: there is no principled difference between the evidential import of these two kinds of evidence. Asking what I think about a matter can be a perfectly legitimate way of gaining more evidence about it.

How do we experience time? When you experience today’s walk as taking twice as long as yesterday’s and then judge that this is so, what is going on? What is it to experience a walk as taking twice as long as another? Do I look at some mental analogue of a watch, one available to me even when I am not wearing a watch on my wrist? Of course not. Nor is there a blinking red light in my visual field that measures how long events take. So do we really experience the durations of events, as opposed to just finding ourselves with judgments concerning their durations? In this dissertation, I defend the idea that we experience durations–that there is something that it is like to experience an event as lasting for a particular amount of time. I develop a theory aimed at explaining what felt duration is, what is distinctive about it, and just how we experience events as having durations of different and yet comparable amounts. It is crucial to this theory that there is a particular duration such that experiencing an event as having that duration has a distinctive phenomenal quality. This is the duration characteristic of what I call a quantum: the longest-lived temporal slice of a situation experienced as a `tightly unified’ whole. While a quantum provides the basis for our subjective system for measuring duration, it also marks a natural division between two distinct ways of experiencing duration: one for long-lived and another for short-lived events. The theory proves fruitful, offering different explanations for various illusions that, as I explain, ought to be distinguished. What is it like to experience the duration of an event? For a long-lived event, it is the impression formed of how many quanta are involved in experiencing the event. For a short-lived event, it is how much of its quantum’s duration the event strikes us as taking up. Because a quantum is the unit of felt duration for both short- and long-lived events, their felt durations are comparable, allowing for a unified system for measuring felt duration.