PHIL 250: Introduction to Symbolic Logic

tennant.9@osu.edu

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Choose Destination My web-page Teaching PHIL 250 PHIL 650 Basic concepts and techniques Truth tables ∀-Introduction ∀-Elimination ∃-Introduction ∃-Elimination ¬-Introduction ¬-Elimination ∧-Introduction ∧-Elimination ∨-Introduction ∨-Elimination →-Introduction →-Elimination Absurdity rule Classical reductio Double negation elimination Law of Excluded Middle Dilemma

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INTRODUCTION RULE FOR CONJUNCTION (∧I)

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A

B

_______________

A∧B

Explanation in words: In order to infer to a conjunctive conclusion A∧B, one must prove the conjunct A and prove the conjunct B. By taking the indicated step of conjunction introduction, one thereby rests the conjunctive conclusion A∧B on the combined assumptions on which the conjuncts A and B respectively rest.

Compare the corresponding elimination rule for ∧

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[¬I] [∧I] [∨I] [→I] [∀I] [∃I]
[¬E] [∧E] [∨E] [→E] [∀E] [∃E]
[EFQ]
[LEM] [Dil] [CR] [DNE]

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