Full Idea
Positivists tend to be prejudiced against ontology, regarding very general questions about what sort of things exist either as meaningless, or as questions to be settled by stipulation.
Clarification
A 'stipulation' is a fairly arbitrary decision
Gist of Idea
Positivists regard ontology as either meaningless or stipulated
Source
report of A.J. Ayer (Language,Truth and Logic [1936]) by Howard Robinson - Perception IX.4
Book Reference
Robinson,Howard: 'Perception' [Routledge 2001], p.227
A Reaction
So much the worse for positivists, because they are missing all the fun. I consider one of the central activities of philosophy to be speculating about explanations. Ontology is at the heart of what explanation aims at.