Full Idea
If a fetus that is being considered for abortion is known to be anencephalic (lacking a brain), this dramatically changes the issue for most people, though not for all.
Gist of Idea
Most people see an abortion differently if the foetus lacks a brain
Source
Daniel C. Dennett (Kinds of Minds [1996], Ch.1)
Book Reference
Dennett,Daniel C.: 'Kinds of Minds' [Phoenix 1997], p.8
A Reaction
A very effective point, as it is hard to see what grounds could be given for not aborting in this case. But the brain then clearly becomes the focus of why abortion is often rejected by many people.