Full Idea
Context does not determine or constitute reference; rather, it is something for the speaker to exploit to enable the listener to determine the intended reference.
Gist of Idea
Context does not create reference; it is just something speakers can exploit
Source
Kent Bach (What Does It Take to Refer? [2006], 22.2 L3)
Book Reference
'Oxford Handbook of Philosophy of Language', ed/tr. Lepore,E/Smith,B [OUP 2008], p.544
A Reaction
Bach thinks linguistic reference is a matter of speaker's intentions, and I think he is right. And this idea is right too. The domain of quantification constantly shifts in a conversation, and good speakers and listeners are sensitive to this.