Demonstratives and indexicals

Demonstratives and indexicals are words and phrases whose interpretations are dependent on features of the context in which they are used. For example, the reference of ‘I’ depends on conditions associated with its use: as you use it, it refers to you; as I use it, it refers to me. In contrast, what ‘the inventor of bifocals’ refers to does not depend on when or where or by whom it is used. Among indexicals are the words ‘here’, ‘now’, ‘today’, demonstrative pronouns such as ‘this’, reflexive, possessive and personal pronouns; and compound phrases employing indexicals, such as ‘my mother’. C.S. Peirce introduced the term ‘indexical’ to suggest the idea of pointing (as in ‘index finger’).

The phenomenon of indexicality figures prominently in recent debates in philosophy. This is because indexicals allow us to express beliefs about our subjective ‘place’ in the world, beliefs which are the immediate antecedents of action; and some argue that such beliefs are irreducibly indexical. For example, my belief that I am about to be attacked by a bear is distinct from my belief that HD is about to be attacked by a bear, since my having the former belief explains why I act as I do (I flee), whereas my having the latter belief explains nothing unless the explanation continues ‘and I believe that I am HD’. It seems impossible to describe the beliefs that prompt my action without the help of ‘I’. Similarly, some have argued that indexical-free accounts of the self or of consciousness are necessarily incomplete, so that a purely objective physicalism is impossible. In a different vein, some (such as Putnam 1975) have argued that our terms for natural substances, kinds and phenomena (‘gold’, ‘water’, ‘light’) are indexical in a way that entails that certain substantive scientific claims – for example, that water is H₂O – are, if true, necessarily true. Thus, reflection on indexicality has yielded some surprising (and controversial) philosophical conclusions.