Full Idea
The constitution theorists, who claim that the sweater and the thread are different things, should offer some explanation of why we tend to say that there is just one thing there. They must simply claim that we 'do not count by identity'.
Gist of Idea
If the constitution view says thread and sweater are two things, why do we talk of one thing?
Source
Katherine Hawley (How Things Persist [2001], 5.8)
Book Reference
Hawley,Katherine: 'How Things Persist' [OUP 2004], p.163
A Reaction
Her example is a sweater knitted from a single piece of thread. Presumably we could count by sortal identity, so there is one thread here, and there is one sweater here. We just can't add the two together. No ontological arithmetic.