Full Idea
The distinction between concrete and abstract objects, or Frege's corresponding distinction between actual and non-actual objects, is not a sharp dichotomy, but resembles a scale upon which objects occupy a range of positions.
Gist of Idea
The distinction of concrete/abstract, or actual/non-actual, is a scale, not a dichotomy
Source
Michael Dummett (Frege philosophy of mathematics [1991], Ch.18)
Book Reference
Dummett,Michael: 'Frege: philosophy of mathematics' [Duckworth 1991], p.239
A Reaction
This might seem right if you live (as Dummett chooses to) in the fog of language, but it surely can't be right if you think about reality. Is the Equator supposed to be near the middle of his scale? Either there is an equator, or there isn't.
Related Idea
Idea 9918 Abstract/concrete is a distinction of kind, not degree [Burgess/Rosen]