Full Idea
The behaviour of subatomic particles cannot be further analysed into structures and this may tempt us to regard these as instances of 'brute' ungrounded dispositions which end any possible regress of explanation.
Gist of Idea
Subatomic particles may terminate explanation, if they lack structure
Source
Stephen Mumford (Dispositions [1998], 06.4)
Book Reference
Mumford,Stephen: 'Dispositions' [OUP 1998], p.133
A Reaction
This seems right, if it is 'structural' explanations we are after (as I think we are) which look for mechanisms. An electron seems to be just three dispositions and no structure, so there is nothing more to say. Ladyman scorns this account.
Related Idea
Idea 14319 Nomothetic explanations cite laws, and structural explanations cite mechanisms [Mumford]