only for reference (Figure 5).
- Two kinds of identity, sense and reference.
Types and tokens
In ordinary language, sense and reference are not always held apart, which
sometimes results in ambiguity. For instance, one could say that (6) contains ten
words or five words:
(6) ’T is so much joy! ’T is so much joy!Both are true; however, in this stanza from Emily Dickinson’s poem, we are
counting different things, ten words, but five different words, distinguished,
respectively, as ‘tokens’ and ‘types’. But what are types? Some philosophers say
they are universals with no spatio-temporal existence. Others say they are
abstract objects of the mind, and still others conceive of types as sets comprising
all actual and possible tokens of them. Think of the letters of the Latin alphabet.
Each of them is an abstraction, a mental image defining a set of all possible
letters that are recognized as A, B, C, etc. Clearly, then, a token is only a token
relative to a type. Conversely, a type exists only through its tokens. In this
interpretation, it is impossible to have a type without at least one token.
The type–token relationship has implications for the concept of identity in many
different fields, such as identical words, identical notes, identical sensations,
identical photographs, identical calendar years, and identical aeroplanes. It has
been widely discussed and has been linked to the mind–body problem. In all
cases, to avoid confusion and logical paradox, it is imperative to make a clear
distinction between type identity and token identity.