Full Idea
If 'P is red' and 'P is orange' are indefinite, then 'P is red and P is orange' seems false, because red and orange are exclusive. But if two conjoined indefinite sentences are false, that makes 'P is red and P is red' false, when it should be indefinite.
Gist of Idea
Conjoining two indefinites by related sentences seems to produce a contradiction
Source
Kit Fine (Vagueness: a global approach [2020], 1)
Book Reference
Fine,Kit: 'Vagueness: a global approach' [OUP 2020], p.10
A Reaction
[compressed] This is the problem of 'penumbral connection', where two indefinite values are still logically related, by excluding one another. Presumably 'P is red and P is of indefinite shape' can be true? Doubtful about this argument.