Full Idea
The identity theorist is committed to the view that there could not be a C-fibre stimulation which was not a pain, nor a pain which was not a C-fibre stimulation; these consequences are certainly surprising and counterintuitive.
Clarification
'C-fibres' were thought to be the physical location of pain
Gist of Idea
Identity theorists seem committed to no-brain-event-no-pain, and vice versa, which seems wrong
Source
Saul A. Kripke (Naming and Necessity lectures [1970], Lecture 3)
Book Reference
Kripke,Saul: 'Naming and Necessity' [Blackwell 1980], p.149
A Reaction
If Kripke saw a glow in an area of his brain every time he felt a pain, he would cease to find it 'counterintuitive'. Far from this conclusion being 'surprising', its opposite is absurd. Pain with no brain event? C-fibres blaze away, and I feel nothing?