Full Idea
If there is a substratum or bare particular within a substance, this gives an explanation of the unity of substances, and it is something which can survive intact when a substance changes.
Gist of Idea
The substratum theory explains the unity of substances, and their survival through change
Source
Cynthia Macdonald (Varieties of Things [2005], Ch.3)
Book Reference
Macdonald,Cynthia: 'Varieties of Things' [Blackwell 2005], p.112
A Reaction
[v. compressed wording] Many problems here. The one that strikes me is that when things change they sometimes lose their unity and identity, and that seems to be decided entirely from observation of properties, not from assessing the substratum.