Full Idea
To be an acid just is to be a proton donor.
Gist of Idea
An acid is just a proton donor
Source
Gideon Rosen (Metaphysical Dependence [2010], 10)
Book Reference
'Modality', ed/tr. Hale,B/Hoffman,A [OUP 2010], p.124
A Reaction
My interest here is in whether we can say that we have found the 'essence' of an acid - so we want to know whether something 'deeper' explains the proton-donation. I suspect not. Being a proton donor happens to have a group of related consequences.