Full Idea
With Kripke's essentialist route to the necessary a posteriori came a sharp distinction between conceivability and genuine possibility - ways things could conceivably be versus ways things could really be (or have been).
Gist of Idea
Kripke's essentialist necessary a posteriori opened the gap between conceivable and really possible
Source
comment on Saul A. Kripke (Naming and Necessity lectures [1970]) by Scott Soames - Significance of the Kripkean Nec A Posteriori p.167
Book Reference
Soames,Scott: 'Philosophical Essays 2:Significance of Language' [Princeton 2009], p.167
A Reaction
A key idea, for me. I love 'could there be a bonfire on the moon?' Imagining it is easy-peasy. 'Could wood combine with oxygen when there is no oxygen present?' We imagined it all right, but did we 'conceive' it?