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''[[Encyclopedia Britannica]]'' declares:

''[[Encyclopedia Britannica]]'' declares:

:"Laws of thought, traditionally, the three fundamental laws of [[logic]]: (1) the [[Law of Non-Contradiction|law of contradiction]], (2) the [[Law of the excluded middle|law of excluded middle]] (or third), and (3) the principle of identity. That is, (1) for all propositions p, it is impossible for both p and not p to be true, or symbolically ∼(p · ∼p), in which ∼ means “not” and · means “and”; (2) either p or ∼p must be true, there being no third or middle true proposition between them, or symbolically p ∨ ∼p, in which ∨ means “or”; and (3) if a propositional function F is true of an individual variable x, then F is indeed true of x, or symbolically F(x) ⊃ F(x), in which ⊃ means “formally implies.” Another formulation of the principle of identity asserts that a thing is identical with itself, or (∀x) (x = x), in which ∀ means “for every”; or simply that x is x."<ref>[https://www.britannica.com/topic/laws-of-thought Laws of Thought], Encyclopedia Britannica</ref>

:"Laws of thought, traditionally, the three fundamental laws of [[logic]]: (1) the [[Law of Non-Contradiction|law of contradiction]], (2) the [[Law of the excluded middle|law of excluded middle]] (or third), and (3) the principle of identity. That is, (1) for all propositions p, it is impossible for both p and not p to be true, or symbolically ∼(p · ∼p), in which ∼ means “not” and · means “and”; (2) either p or ∼p must be true, there being no third or middle true proposition between them, or symbolically p ∨ ∼p, in which ∨ means “or”; and (3) if a propositional function F is true of an individual variable x, then F is indeed true of x, or symbolically F(x) ⊃ F(x), in which ⊃ means “formally implies.” Another formulation of the principle of identity asserts that a thing is identical with itself, or (∀x) (x = x), in which ∀ means “for every”; or simply that x is x."<ref>[https://www.britannica.com/topic/laws-of-thought Laws of Thought], Encyclopedia Britannica</ref>

==References==

==References==

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[[Category: Logic]]

[[Category: Logic]]