Full Idea
We can analyse qualitative identity in terms of numerical identity, by saying that x and y are type-identical if there is a single type T that x and y both are, i.e. they both exemplify the same type.
Gist of Idea
Qualitative identity can be analysed into numerical identity of the type involved
Source
Colin McGinn (Logical Properties [2000], Ch.1)
Book Reference
McGinn,Colin: 'Logical Properties' [OUP 2003], p.3
A Reaction
This just seems to shift the problem onto the words 'are' and 'exemplify'. This takes us back to the problem of things 'partaking' of Plato's Forms. Better to say that qualitative identity isn't identity - it is resemblance (see Idea 6045).
Related Idea
Idea 6045 It is best to drop types of identity, and speak of 'identity' or 'resemblance' [McGinn]