Combining Philosophers

Ideas for Archimedes, Cardinal/Hayward/Jones and Gilbert Harman

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8 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic

3093	Any two states are logically linked, by being entailed by their conjunction [Harman]
	Full Idea: Any two states of affairs are logically connected, simply because both are entailed by their conjunction.
	From: Gilbert Harman (Thought [1973], 8.1)

12595	We have a theory of logic (implication and inconsistency), but not of inference or reasoning [Harman]
	Full Idea: There is as yet no substantial theory of inference or reasoning. To be sure, logic is well developed; but logic is not a theory of inference or reasoning. Logic is a theory of implication and inconsistency.
	From: Gilbert Harman ((Nonsolipsistic) Conceptual Role Semantics [1987], 12.2.2)
	A reaction: One problem is that animals can draw inferences without the use of language, and I presume we do so all the time, so it is hard to see how to formalise such an activity.

5. Theory of Logic / A. Overview of Logic / 6. Classical Logic

3098	Deductive logic is the only logic there is [Harman]
	Full Idea: Deductive logic is the only logic there is.
	From: Gilbert Harman (Thought [1973], 10.4)

5. Theory of Logic / B. Logical Consequence / 5. Modus Ponens

3094	You don't have to accept the conclusion of a valid argument [Harman]
	Full Idea: We may say "From P and If-P-then-Q, infer Q" (modus ponens), but there is no rule of acceptance to say that we should accept Q. Maybe we should stop believing P or If-P-then-Q rather than believe Q.
	From: Gilbert Harman (Thought [1973], 10.1)

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

3084	Our underlying predicates represent words in the language, not universal concepts [Harman]
	Full Idea: The underlying truth-conditional structures of thoughts are language-dependent in the sense that underlying predicates represent words in the language rather than universal concepts common to all languages.
	From: Gilbert Harman (Thought [1973], 6.3)

3080	Logical form is the part of a sentence structure which involves logical elements [Harman]
	Full Idea: The logical form of a sentence is that part of its structure that involves logical elements.
	From: Gilbert Harman (Thought [1973], 5.2)

3081	A theory of truth in a language must involve a theory of logical form [Harman]
	Full Idea: Some sort of theory of logical form is involved in any theory of truth for a natural language.
	From: Gilbert Harman (Thought [1973], 5.2)

5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / d. and

12597	I might accept P and Q as likely, but reject P-and-Q as unlikely [Harman]
	Full Idea: Principles of implication imply there is not a purely probabilistic rule of acceptance for belief. Otherwise one might accept P and Q, without accepting their conjunction, if the conjuncts have a high probability, but the conjunction doesn't.
	From: Gilbert Harman ((Nonsolipsistic) Conceptual Role Semantics [1987], 12.2.2)
	A reaction: [Idea from Scott Soames] I am told that my friend A has just won a very big lottery prize, and am then told that my friend B has also won a very big lottery prize. The conjunction seems less believable; I begin to suspect a conspiracy.