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Single Idea 21698

[filed under theme 5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic ]

Full Idea

Much of the theory of relations can be developed as a virtual theory, in which we seem to talk of relations, but can explain our notation in terms {finally] of just the logic of truth-functions, quantification and identity. The exception is ancestrals.

Gist of Idea

All relations, apart from ancestrals, can be reduced to simpler logic

Source

Willard Quine (Lecture on Nominalism [1946], §8)

Book Ref

'Oxford Studies in Metaphysics vol.4', ed/tr. Zimmerman,Dean W. [OUP 2008], p.14


A Reaction

The irreducibility of ancestrals is offered as a reason for treating sets as universals.


The 11 ideas with the same theme [role of terms which connect objects into relationships]:

De Morgan found inferences involving relations, which eluded Aristotle's syllogistic [De Morgan, by Hart,WD]
De Morgan started the study of relations and their properties [De Morgan, by Walicki]
The logic of relatives relies on objects built of any relations (rather than on classes) [Peirce]
Relations are functions with two arguments [Frege]
In 'Principia' a new abstract theory of relations appeared, and was applied [Russell/Whitehead, by Gödel]
All relations, apart from ancestrals, can be reduced to simpler logic [Quine]
We can use mereology to simulate quantification over relations [Lewis]
Relations need terms, so they must be second-order entities based on first-order tropes [Campbell,K]
A relation is either a set of sets of sets, or a set of sets [Burgess/Rosen]
The mathematics of relations is entirely covered by ordered pairs [Chihara]
'Before' and 'after' are not two relations, but one relation with two orders [Hossack]