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Ideas for 'Material Beings', 'What is 'naturalized epistemology'?' and 'Intellectual Autobiography'

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7 ideas

5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle

17587	The 'Law' of Excluded Middle needs all propositions to be definitely true or definitely false [Inwagen]
	Full Idea: I think the validity of the 'Law' of Excluded Middle depends on the assumption that every proposition is definitely true or definitely false.
	From: Peter van Inwagen (Material Beings [1990], 18)
	A reaction: I think this is confused. He cites vagueness as the problem, but that is a problem for Bivalence. If excluded middle is read as 'true or not-true', that leaves the meaning of 'not-true' open, and never mentions the bivalent 'false'.

5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic

18897	Predicate logic has to spell out that its identity relation '=' is an equivalent relation [Sommers]
	Full Idea: Because predicate logic contrues identities dyadically, its account of inferences involving identity propositions needs laws or axioms of identity, explicitly asserting that the dyadic realtion in 'x=y' possesses symmetry, reflexivity and transitivity.
	From: Fred Sommers (Intellectual Autobiography [2005], 'Syllogistic')

5. Theory of Logic / E. Structures of Logic / 1. Logical Form

18893	Translating into quantificational idiom offers no clues as to how ordinary thinkers reason [Sommers]
	Full Idea: Modern predicate logic's methods of justification, which involve translation into an artificial quantificational idiom, offer no clues to how the average person, knowing no logic and adhering to the vernacular, is so logically adept.
	From: Fred Sommers (Intellectual Autobiography [2005], Intro)
	A reaction: Of course, people are very logically adept when the argument is simple (because, I guess, they can test it against the world), but not at all good when the reasoning becomes more complex. We do, though, reason in ordinary natural language.

5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / c. not

18903	Sommers promotes the old idea that negation basically refers to terms [Sommers, by Engelbretsen]
	Full Idea: If there is one idea that is the keystone of the edifice that constitutes Sommers's united philosophy it is that terms are the linguistic entities subject to negation in the most basic sense. It is a very old idea, tending to be rejected in modern times.
	From: report of Fred Sommers (Intellectual Autobiography [2005]) by George Engelbretsen - Trees, Terms and Truth 2
	A reaction: Negation in modern logic is an operator applied to sentences, typically writing '¬Fa', which denies that F is predicated of a, with Fa being an atomic sentence. Do we say 'not(Stan is happy)', or 'not-Stan is happy', or 'Stan is not-happy'? Third one?

5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic

17558	Variables are just like pronouns; syntactic explanations get muddled over dummy letters [Inwagen]
	Full Idea: Explanations in terms of syntax do not satisfactorily distinguish true variables from dummy or schematic letters. Identifying variables with pronouns, however, provides a genuine explanation of what variables are.
	From: Peter van Inwagen (Material Beings [1990], 02)
	A reaction: I like this because it shows that our ordinary thought and speech use variables all the time ('I've forgotten something - what was it?'). He says syntax is fine for maths, but not for ordinary understanding.

5. Theory of Logic / E. Structures of Logic / 7. Predicates in Logic

18894	Predicates form a hierarchy, from the most general, down to names at the bottom [Sommers]
	Full Idea: We organise our concepts of predicability on a hierarchical tree. At the top are terms like 'interesting', 'exists', 'talked about', which are predicable of anything. At the bottom are names, and in between are predicables of some things and not others.
	From: Fred Sommers (Intellectual Autobiography [2005], 'Category')
	A reaction: The heirarchy seem be arranged simply by the scope of the predicate. 'Tallest' is predicable of anything in principle, but only of a few things in practice. Is 'John Doe' a name? What is 'cosmic' predicable of? Challenging!

5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / b. The Heap paradox ('Sorites')

17583	There are no heaps [Inwagen]
	Full Idea: Fortunately ....there are no heaps.
	From: Peter van Inwagen (Material Beings [1990], 18)
	A reaction: This is the nihilist view of (inorganic) physical objects. If a wild view solves all sorts of problems, one should take it serious. It is why I take reductive physicalism about the mind seriously. (Well, it's true, actually)