Full Idea
Analytical moral philosophers resist emotivism because moral reasoning does occur, but there can be logical linkages between various moral judgements of a kind that emotivism could not allow for ('therefore' and 'if...then' express no moral feelings).
Gist of Idea
Emotivism cannot explain the logical terms in moral discourse ('therefore', 'if..then')
Source
Alasdair MacIntyre (After Virtue: a Study in Moral Theory [1981], Ch. 2)
Book Reference
MacIntyre,Alasdair: 'After Virtue: a Study in Moral Theory' [Duckworth 1982], p.19
A Reaction
This is the 'Frege-Geach Problem', nicely expressed, and is the key reason why emotivism seems unacceptable - it is a theory about language, but it just doesn't explain moral discourse sufficiently.