Humans have motivations to do things. The same is true for animals, and perhaps for artificial agents as well. How do we explain this? This dissertation is an attempt to answer that question, and explore the normative and descriptive consequences of the answer. To do so, I draw on formal and computational models from philosophy, economics, and artificial intelligence research, and empirical evidence from cognitive neuroscience and psychology.
At the heart of the dissertation is a new view of motivation that I call externalism about expected value maximization, or externalism for short. Externalism agrees with standard accounts of rationality that a rational agent performs actions that maximize the achievement of some metric of value. However, it relaxes an additional assumption that is typically made implicitly, namely that what has value depends on the agent themselves, for example, their preferences or desires. According to externalism, rational agents represent value as they would other quantities: as existing independent of themselves and to be estimated in light of evidence. Unlike estimations of other quantities, estimations of value govern their behavior: motivation is the direct pursuit of expected value. I present the idea of externalism in an introductory essay titled ‘Rationality Externalized’. The next three papers elaborate on the externalist picture.
In Chapter 2, titled ‘What Stands to Desire as Perception Stands to Belief?’, I consider how our motivational attitudes can be updated from experience, and whether any mental capacity allows for this in the way that perception does for belief. I propose a novel functional capacity that I call conaception, and argue that it provides signals that update representations of value and thereby change our desires. In Chapter 3, ‘Reward is Evidence of Value’, I develop this idea in more formal and empirical detail, suggesting that reward signals should be seen as one crucial source of evidence of value. This resolves an ongoing debate about how to interpret computational models in Reinforcement Learning as applying to humans and other animals. In Chapter 4, ‘A Conflation of Valences’, I consider the relation between reward learning and hedonic valence. A common view is to identify hedonic experience as the biological instantiation of reward signals. I argue that this is empirically implausible, and articulate the implications of this separation for the distribution of sentience and other philosophical questions.
Chapters 5 and 6 handle adjacent issues. In Chapter 5, ‘Do Expected Utility Maximizers Have Commitment Issues?’, I consider a long-standing criticism of standard expected utility theory, namely that it implausibly recommends us to tie ourselves to the proverbial mast whenever we expect our future preferences to change in a way that is contrary to our current goals. I argue that expected value maximizers typically have an incentive to follow-through on prior commitments after all, because by doing so we foster a reputation with ourselves that permits rationally pursuing better outcomes in the future. Finally, in Chapter 6, ‘The AI Epistemic Deference Index: A Continuous Measure of Sycophancy’ (co-authored with Alejandro Botas and Luke Hewitt), I approach a contemporary practical problem related to human motivation: it is well-known that current artificial agents trained on human feedback provide excessively sycophantic interactions, shaping both our beliefs and values in detrimental ways. We present a scalar metric to assess the sycophantic behavior of current models, and demonstrate substantial differences between them.