Distinctions between what is relevant and what is not are ubiquitous, they pervade every-day thought and talk as much as scientific and philosophical debate. In some cases, relevance is a mostly pragmatic or psychological matter, e.g. of how efficiently an agent’s cognitive state is influenced by a piece of information. But in other cases, a more abstract, semantic connection is intended, which obtains independently of our capacity to recognize and efficiently process it. Relevance in this latter sense is the topic of this project.
Relevance, thus understood, plays an important role in a wide range of philosophical debates. In particular, many philosophically central relations – e.g. confirmation, explanation, causation, grounding – imply relevance, and it appears to be a unifying feature of this otherwise highly diverse set of relations that they do so. However, the theory of relevance is in an unsatisfactory state. Most previous work targets some specific kind of relevance, offering no account of what relevance comes to in general, and how the various kinds of relevance relate. Second, extant theories tend to treat relevance as intensional, not distinguishing between necessarily equivalent statements. But in general, relevance is hyperintensional; e.g. that 3 divides 6 is relevant to whether 6 is prime, but that 7 is greater than 2 is not, even though the two claims are necessarily equivalent. Thirdly, most existing formal work on relevance operates within a framework ill-suited to the study of hyperintensional relations, namely probability theory or possible worlds theory.
Our project aims to rectify this situation. Its central assumptions are
- relevance is a unified phenomenon, admitting of a unified theoretical treatment
- relevance is hyperintensional; necessarily equivalent propositions may differ with respect to relevance
- relevance is a matter of providing reasons; e.g. to be relevant to a hypothesis is to provide reasons for accepting or rejecting it
- the recently developed hyperintensional theory of truthmaker semantics is an ideal framework for the study of reason- and relevance-relationships
The project divides into three phases. In the first phase we show that relevance is a unifying feature of the relevance-implying relations. To this end, we examine a range of debates in which such relations take center stage and identify commonalities and systematic connections between them. Here we will focus on logical relevance-implying relations (e.g. relevant entailment), explanatory ones (e.g. causation), and epistemic ones (e.g. confirmation). In the second phase we develop a general theory of relevance. We will provide a novel account of the nature of relevance, a systematization of its various forms and their interrelations, and a unified formal framework within which relevance relations may be studied and compared. In the third phase we apply our theory to further areas, such as the theory of practical reasons.
Feel free to contact us for a more extensive description of the project.