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Single Idea 13041

[filed under theme 9. Objects / C. Structure of Objects / 8. Parts of Objects / b. Sums of parts ]

Full Idea

A collection has a determinate number of members, whereas a fusion may be carved up into parts in various equally valid (although perhaps not equally interesting) ways.

Gist of Idea

Collections have fixed members, but fusions can be carved in innumerable ways

Source

Michael Potter (Set Theory and Its Philosophy [2004], 02.1)

Book Ref

Potter,Michael: 'Set Theory and Its Philosophy' [OUP 2004], p.22


A Reaction

This seems to sum up both the attraction and the weakness of mereology. If you doubt the natural identity of so-called 'objects', then maybe classical mereology is the way to go.


The 14 ideas from 'Set Theory and Its Philosophy'

Set theory's three roles: taming the infinite, subject-matter of mathematics, and modes of reasoning [Potter]
Supposing axioms (rather than accepting them) give truths, but they are conditional [Potter]
We can formalize second-order formation rules, but not inference rules [Potter]
Mereology elides the distinction between the cards in a pack and the suits [Potter]
Collections have fixed members, but fusions can be carved in innumerable ways [Potter]
Nowadays we derive our conception of collections from the dependence between them [Potter]
Priority is a modality, arising from collections and members [Potter]
If dependence is well-founded, with no infinite backward chains, this implies substances [Potter]
If set theory didn't found mathematics, it is still needed to count infinite sets [Potter]
Usually the only reason given for accepting the empty set is convenience [Potter]
A relation is a set consisting entirely of ordered pairs [Potter]
Infinity: There is at least one limit level [Potter]
It is remarkable that all natural number arithmetic derives from just the Peano Axioms [Potter]
The 'limitation of size' principles say whether properties collectivise depends on the number of objects [Potter]