Full Idea
The most extreme critics of metaphysics base their critique on sweeping views about language (logical positivism), or knowledge (empiricism), ...but this notoriously threatens the science of unobservables as much as it threatens metaphysics.
Gist of Idea
Extreme doubts about metaphysics also threaten to undermine the science of unobservables
Source
Theodore Sider (Writing the Book of the World [2011], 05.1)
Book Reference
Sider,Theodore: 'Writing the Book of the World' [OUP 2011], p.67
A Reaction
These criticisms also threaten speculative physics (even about what is possibly observable).