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logical truth

Subject Philosophy

DOI: 10.1111/b.9781405106795.2004.x


L ogic, epistemology A logical symbol or logical formula can be a logical truth because it is true under all interpretations . A statement or proposition is logically true if it is validly deduced in a logical system. In this sense, a logical truth is generally a theorem of a logical system. More often, we say that a statement is a logical truth because it is an instance of a valid logical form . For example, “A house cannot be both warm and not warm.” The logical form of this sentence is “not both p and nonp,” and it is thus in accord with the principle of noncontradiction. If a statement is logically true, then it is analytic and is necessarily true. On the contrary, if a statement violates a logically valid form, that is, if its logical form conflicts with some logical principle, it is logically false or a logical falsity. If a statement is logically false, it is necessarily false. Accounts of the kind of logical truth that depends upon the meaning of the expressions contained in a proposition have come under pressure from Quine 's rejection of the analytic-synthetic distinction and the notions of synonymy and meaning . Without reliance on meaning, a logical truth becomes any truth which can be obtained from a valid logical scheme. “A logical schema is valid if every sentence obtainable from it by substituting sentences for simple sentence is true. A logical ... log in or subscribe to read full text

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