The problem addressed in ESSINDEX is the “problem of the essential indexical” in the contemporary philosophy of language and mind. Indexicals are words like ‘I’, ‘here’, ‘now’, ‘that’, etc. whose referent (what they designate) varies according to the context of their use. Pioneers of modern semantics regarded indexicality as a dispensable feature of the words whereby we express thoughts – and even as a defect of natural languages, which, like other forms of context-dependency (such as ambiguity or vagueness), ought to be eliminated from the ideal, logical languages better suited to the purposes of knowledge and science. However, around 1970, philosophers noticed that some thoughts cannot be expressed without the help of indexicals. This is the so-called “problem of the essential indexical,” which suggests that indexicality, far from being a dispensable feature of the words whereby we express our thoughts (linguistic indexicality), is much more fundamentally an essential feature of certain thoughts, which represent the world from an irreducibly first-person, egocentric perspective (mental indexicality). Because of their subjective, 'perspectival' nature, such indexical thoughts pose deep challenges to what are common and otherwise plausible objectivist, 'propositionalist' doctrines about the semantics of mental states like beliefs.
Like for other fundamental philosophical themes, developing an understanding of mental indexicality is of general importance for society. The phenomenon questions mysterious features of what is most distinctive about human life and experience: the human mind. Mental indexicality is now widely regarded as a nexus between classical issues in philosophy of language, philosophy of mind, semantics, pragmatics, epistemology, and philosophy of science, having to do with subjectivity and the first person in the realms of language, thought, knowledge, perception, and consciousness.
But while the phenomenon of essential indexicality is connected to old themes in philosophy, intense debates are currently raging about its extent, its varieties, and its semantics. The project ESSINDEX contributes to these ongoing debates by developing an original account of what is distinctive about indexical thoughts. In particular, it explores a new general hypothesis, according to which the reason why the problem of the essential indexical has sounded so intractable thus far is that two different problems were conflated from the start. Once the two problems are properly distinguished, surprising and groundbreaking solutions become accessible for each problem.
The main conclusions of ESSINDEX are (1) that the general hypothesis of an overlooked distinction between two different problems stands up to scrutiny, and (2) that one of the possible accounts of the two problems envisaged in the project is particularly successful and has general consequences for philosophy and linguistics.