Argumentation 101 - Reductio ad absurdum
In symbols:See here for background on the following substitutions:
To disprove p: one uses the tautology (p → (R ∧ ¬R)) → ¬p, where R is any proposition and the ∧ symbol is taken to mean “and”. Assuming p, one proves R and ¬R, and concludes from this that p → (R ∧ ¬R). This and the tautology together imply ¬p.
1) Let ‘p’ equal ‘Pilgrim is correct’.
2) Let ‘R’ equal ‘its good when UW students suppress free speech’.
To disprove p or ‘Pil is correct’: one uses the tautology (p → (R ∧ ¬R)) → ¬p, where R is ‘its good when UW students suppress free speech’ and the ∧ symbol is taken to mean “and”.
Assuming p, one proves R and ¬R, and concludes from this that p → (R ∧ ¬R).
If Pil is correct then its good when UW students suppress free speech and its not good when UW students suppress free speech.
This and the tautology together imply ¬p.
If the assumption that Pil is correct leads to a contradiction, then Pil is not correct.
Pil is not correct.