structure for 'Thought'    |     alphabetical list of themes    |     unexpand these ideas

18. Thought / E. Abstraction / 4. Abstracta by Example

[defining abstract entities by offering examples]

2 ideas
The Way of Example compares donkeys and numbers, but what is the difference, and what are numbers? [Lewis]
     Full Idea: The Way of Example says concrete entities are things like donkeys and puddles, but abstract entities are things like numbers. That gives us little guidance. There are no uncontroversial accounts of numbers, and donkeys and number differ in too many ways.
     From: David Lewis (On the Plurality of Worlds [1986], 1.7)
     A reaction: That demolishes that fairly swiftly. It may be unfair to demand an agreed account of numbers, but the respect(s) in which donkeys and numbers differ needs to be spelled out before anything useful has been said.
'Abstract' is unclear, but numbers, functions and sets are clearly abstract [Field,H]
     Full Idea: The term 'abstract entities' may not be entirely clear, but one thing that does seem clear is that such alleged entities as numbers, functions and sets are abstract.
     From: Hartry Field (Science without Numbers [1980], p.1), quoted by JP Burgess / G Rosen - A Subject with No Object I.A.1.a
     A reaction: Field firmly denies the existence of such things. Sets don't seem a great problem, if the set is a herd of elephants, but the null and singleton sets show up the difficulties.