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9193
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ZF set theory has variables which range over sets, 'equals' and 'member', and extensionality [Dummett]
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Full Idea:
ZF set theory is a first-order axiomatization. Variables range over sets, there are no second-order variables, and primitive predicates are just 'equals' and 'member of'. The axiom of extensionality says sets with the same members are identical.
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From:
Michael Dummett (The Philosophy of Mathematics [1998], 7)
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A reaction:
If the eleven members of the cricket team are the same as the eleven members of the hockey team, is the cricket team the same as the hockey team? Our cricket team is better than our hockey team, so different predicates apply to them.
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9195
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Intuitionists reject excluded middle, not for a third value, but for possibility of proof [Dummett]
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Full Idea:
It must not be concluded from the rejection of excluded middle that intuitionistic logic operates with three values: true, false, and neither true nor false. It does not make use of true and false, but only with a construction being a proof.
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From:
Michael Dummett (The Philosophy of Mathematics [1998], 8.1)
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A reaction:
This just sounds like verificationism to me, with all its problems. It seems to make speculative statements meaningless, which can't be right. Realism has lots of propositions which are assumed to be true or false, but also unknowable.
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9186
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First-order logic concerns objects; second-order adds properties, kinds, relations and functions [Dummett]
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Full Idea:
First-order logic is distinguished by generalizations (quantification) only over objects: second-order logic admits generalizations or quantification over properties or kinds of objects, and over relations between them, and functions defined over them.
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From:
Michael Dummett (The Philosophy of Mathematics [1998], 3.1)
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A reaction:
Second-order logic was introduced by Frege, but is (interestingly) rejected by Quine, because of the ontological commitments involved. I remain unconvinced that quantification entails ontological commitment, so I'm happy.
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9187
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Logical truths and inference are characterized either syntactically or semantically [Dummett]
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Full Idea:
There are two ways of characterizing logical truths and correct inference. Proof-theoretic or syntactic characterizations, if the formalization admits of proof or derivation; and model-theoretic or semantic versions, being true in all interpretations.
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From:
Michael Dummett (The Philosophy of Mathematics [1998], 3.1)
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A reaction:
Dummett calls this distinction 'fundamental'. The second one involves truth, and hence meaning, where the first one just responds to rules. ..But how can you have a notion of correctly following a rule, without a notion of truth?
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22602
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Over several centuries a set of eight main liberal values was established [Dunt]
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Full Idea:
Over the centuries liberal values were established: freedom of the individual, reason, consent in government, individual rights, the separation of powers, protection of minorities, autonomy, and moderation.
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From:
Ian Dunt (How to be a Liberal [2020], 13)
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A reaction:
What's not to like? 'Moderation' might be a sticking point, for anyone who thinks that very large social changes are needed.
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22596
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No government, or the whole nation, can control an individual beyond legitimate scope [Dunt]
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Full Idea:
When a government of any sort puts a threatening hand on that part of individual life beyond its proper scope, …even if it were the whole nation, except for the man it is harassing, it would be no more legitimate for that.
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From:
Ian Dunt (How to be a Liberal [2020]), quoted by Ian Dunt - How to be a Liberal 4
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A reaction:
The obvious question is what counts as 'proper scope' - and who gets to define it? If the individual can define that, then criminals can appeal to this principle. The state must be persuaded of it, then asked to stick to it during conflicts.
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22603
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Laissez-faire liberalism failed to give people the protections and freedoms needed for a good life [Dunt]
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Full Idea:
Laissez-faire liberalism failed, because it did not offer people protections and real freedom - against discrimination, insecure work, educational disadvantage, lack of social respect, absence of representation. It was cold, distant, and ineffective.
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From:
Ian Dunt (How to be a Liberal [2020], 13)
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A reaction:
A very nice summary, which I take to be correct.
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