The homework questions are proofs intro.
Each of these derivations (proofs) are demonstrations of VALIDITY. Specifically, they are
demonstrations that the goal sentence (the conclusion) validly follows from the starting
assumptions (premises).
1) Write the goal sentence.
2) Determine the main logical operator of sentence to determine what kind of sentence
it is – an atomic sentence, a conjunction, a disjunction, etc.
3) Figure out what you need to do to get the goal sentence. For instance:
a. If the sentence is a conjunction, you must get each conjunct on a separate line
of the derivation.
b. Each conjunct must be derived by locating where it appears in the starting
assumptions (SA)/premises, and then applying the appropriate Introduction
and Elimination rules to get that conjunct.
4) No two different proofs will be exactly the same. The only way to get good at
proofs is to practice, practice, practice.
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