Topics of Thought

This book concerns mental states such as thinking that Obama is tall, imagining that there will be a climate change catastrophe, knowing that one is not a brain in a vat, or believing that Martina Navratilova is the greatest tennis player ever. Such states are usually understood as having intentionality, that is, as being about things or situations to which the mind is directed. The contents of such states are often taken to be propositions. The book presents a new framework for the logic of thought, so understood—an answer to the question: Given that one thinks (believes, knows, etc.) something, what else must one think (ditto) as a matter of logic? This should depend on the propositions which make for the contents of the relevant thoughts. And the book defends the idea that propositions should be individuated hyperintensionally, i.e. not just by the sets of worlds at which they are true (as in standard ‘intensional’ possible worlds semantics), but also by what they are about: their topic or subject matter. Thus, the logic of thought should be ‘topic-sensitive’. After the philosophical foundations have been presented in Chapters 1−2, Chapter 3 develops a theory of Topic-Sensitive Intentional Modals (TSIMs): modal operators representing attitude ascriptions, which embed a topicality or subject matter constraint. Subsequent chapters explore applications ranging from mainstream epistemology (dogmatism, scepticism, fallibilism: Chapter 4), to the nature of suppositional thinking and imagination (Chapter 5), conditional belief and belief revision (Chapter 6), framing effects (Chapter 7), probabilities and indicative conditionals (Chapter 8)

Impossible worlds

The latter half of the twentieth century witnessed an ‘intensional revolution’, a great collective effort to analyse notions which are absolutely fundamental to our understanding of the world and of ourselves—from meaning and information to knowledge, belief, causation, essence, supervenience, conditionality, as well as nomological, metaphysical, and logical necessity—in terms of a single concept. This was the concept of a possible world: a way things could have been. Possible worlds found applications in logic, metaphysics, semantics, game theory, information theory, artificial intelligence, and the philosophy of mind and cognition. However, possible worlds analyses have been facing numerous problems. This book traces them all back to hyperintensionality: the need for distinctions more fine-grained than the possible worlds apparatus can easily represent. It then introduces impossible worlds—ways things could not have been—as a general tool for modelling hyperintensional phenomena. The book discusses the metaphysics of impossible worlds and applies them to a range of central topics and open issues in logic, semantics, and philosophy: from the problem of logical omniscience in epistemic logic, to the semantics of non-classical logics, the modelling of imagination and mental simulation, the analysis of information and informative inference, truth in fiction, and counterpossible reasoning.Publisher PD

Sensory experience and the sensible qualities

textMy dissertation defends a package of interrelated positions on the metaphysics of the sensible qualities (shape, color, pitch, loudness, flavor, heat, cold, etc.) and sensory experience. It is organized around four questions at the core of philosophical theorizing about the sensible qualities. The first is the question of reductionism: are the sensible qualities reducible to either physical properties (i.e. properties definable in the canonical vocabulary of the physical sciences) or response-dependent properties (e.g. Lockean dispositions to affect perceivers in certain ways)? I put forward novel arguments and refined versions of traditional arguments in support of a negative answer to this question. For at least some of the sensible qualities, including many of those traditionally classified as “secondary qualities,” reductionism is untenable. If I am correct that the sensible qualities are not reducible to physical or response-dependent properties of external objects, the next question arises: do they belong to external objects at all? This is the question of realism. Many philosophers have held that a negative answer to the question of reductionism leads--or should lead--to a negative answer to the question of realism. Against these philosophers, I defend an affirmative answer to the question of realism and respond to arguments from non-reductionism to irrealism. If I am correct that the sensible qualities really belong to external objects but aren’t reducible to any of their physical properties, a third question arises: how are the sensible qualities (especially the so-called “secondary qualities”) related to physical reality? This is the question of integration, a special case of the more general question of how, in Sellars’s terminology, the Manifest Image is related to the Scientific Image. In response to this question, I develop and defend a theory structurally parallel to Russellian monist positions on the mind-body problem. I argue that the Russellian monist framework is actually poorly suited to answer the question it was originally designed to answer--the question of how conscious experience is related to physical reality--but well suited to answer the corresponding question about the sensible (especially secondary) qualities.Philosoph

Decision, Causality, and Predetermination

Evidential decision theory (EDT) says that the choiceworthiness of an option depends on its evidential connections to possible outcomes. Causal decision theory (CDT) holds that it depends on your beliefs about its causal connections. While Newcomb cases support CDT, Arif Ahmed has described examples that support EDT. A new account is needed to get all cases right. I argue that an option A’s choiceworthiness is determined by the probability that a good outcome ensues at possible A-worlds that match actuality in the facts causally unaffected by your decision (the “unaffected facts”). Moreover, you should evaluate A on the assumption that A is compossible with the unaffected facts. This view entails that you should use EDT when evaluating A on the assumption that the unaffected facts determine your action, but use CDT when assessing A on the opposite assumption. A’s choiceworthiness equals a weighted average of these conditional assessments. The weights are determined by your beliefs about whether the unaffected fact determine your action. This account gets both Newcomb and Ahmed cases right. According to an influential view, whether you take the unaffected facts to determine your action can make a difference to whether you can regard yourself as free and the action as being under your control. While my account is neutral on this issue, it entails that whether you take the unaffected facts to determine your action is important in a different way: it matters to whether you should follow EDT or CDT

Uncertainty for uncertain decision makers

First Chapter - While mainstream decision theory only allows for variations in the severity of uncertainty, the plurality of labels with which uncertainty has been referred to in the literature and the variety of doubts that decision makers can have seem to suggest that there are different types of uncertainty. Given the importance that uncertainty has in almost any decision, understanding this plurality can be helpful to decide effectively. I propose an account of uncertainty as based on a disagreement between reasons supporting alternative mental attitudes. Under this account, dealing with uncertainty means dealing with disagreement; however, this disagreement can be radical, i.e. persistent under ideal cognitive and epistemic conditions. When this is the case, the disagreement and therefore the uncertainty cannot be resolved with an increase in evidence. I draw a typology of uncertainty reflecting the conditions that must obtain for the possibility of radical disagreement, and I trace the role that each of the types identified plays in decision making.Second Chapter - Decision theories have largely ignored the step of decision making in which the agent models the situation. Given that a decision can be represented with different models, and that these can lead to different recommendations, then without a principled way to assess them the agent’s choice is under-determined. As models require the agent to select the aspects that matter to the decision, an account of rational decision modelling must include a notion of relevance. I propose that the most rational model is the one taking into account all and only the considerations relevant for the decision. I define relevance for a decision as a matter of providing reasons for some option, and I identify four functional types of reasons leading to four corresponding types of relevance. I focus on what I call “constitutive relevance”, which provides the content of the decision model, and propose a formal definition of this concept.Third Chapter - The increasing success of the evidence-based policy movement is raising the demand for empirically informed decision making. As arguably any policy decision happens under conditions of uncertainty, following our best available evidence to reduce the uncertainty seems a requirement of good decision making. However, not all the uncertainty faced by decision makers can be resolved by evidence. In this paper, we build on a philosophical analysis of uncertainty to identify the boundaries of scientific advice in policy decision making. We argue that the authority of scientific advisors is limited to cognitive uncertainty and cannot extend beyond it. While the appeal of evidence-based policy rests on a view of scientific advice as limited to cognitive uncertainty, in practice there is a risk of over-reliance on experts beyond the legitimate scope of their authority. We conclude by applying our framework to a real-world case of evidence based policy, where experts have overstepped their boundaries by ignoring non-cognitive types of uncertainty.Fourth Chapter - The COVID-19 pandemic has presented the world with a series of new challenges, but the policy response may be difficult due to the severe uncertainty of our circumstances. While pressure to take timely action may push towards less inclusive decision procedures, in this paper I argue that precisely this uncertainty provides both democratic and epistemic reasons to include stakeholders in our collective decision making