When I think about how I landed at the idea for this dissertation, one memory from my rst semester at Penn sticks in my mind. It was part-way through a seminar in Philosophy of Psychology: we were discussing the nature of cognition, or mental representation, or some similarly tricky concept. (Actually, maybe we were discussing concepts.) is being a philosophy class, no solid denition was forthcoming. Nor was much else agreed upon by everyone in the room. e assortment of senior undergraduates, graduate students at various stages of academic progression, and a professor well versed on the subject all muttered didently about it for a while. Eventually the professor, one Gary Hateld, posed a question that brought the whole discussion into context