Full Idea
For four-dimensionalists intrinsic change is difference between successive temporal parts.
Gist of Idea
4D says intrinsic change is difference between successive parts
Source
Theodore Sider (Four Dimensionalism [2001], 3.2)
Book Reference
Sider,Theodore: 'Four Dimensionalism' [OUP 2003], p.56
A Reaction
This attempts a reply to the commonest criticism of four-dimensionalism - that you can't explain change if you don't have one enduring thing which undergoes the change. I get stuck of the question 'how big (temporally) is a part?'.