Full Idea
We cannot accept the existence of vague objects, according to Evans's argument that there cannot be indeterminacy of identity. ...From the assumption that it is indeterminate whether a = b, we conclude, determinately, that it's not the case that a = b.
Gist of Idea
If a=b is indeterminate, then a=/=b, and so there cannot be indeterminate identity
Source
report of Gareth Evans (Can there be Vague Objects? [1978]) by Amie L. Thomasson - Ordinary Objects 05.6
Book Reference
Thomasson,Amie L.: 'Ordinary Objects' [OUP 2010], p.107
A Reaction
I think we should keep intrinsic identity separate from identity between entities. A cloud can be clearly identified, while being a bit fuzzy. It is only when you ask whether we saw the same cloud that Evans's argument seems relevant.