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Public Alpha

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Public Alpha

Reductio Ad Absurdum

The celebrated classical principle of Reductio says that if you can infer a contradiction from an assumption then you can discharge that assumption and conclude the negation of what you assumed.

Constants: ~
Systems: LRC

Start a Problem →

Reductio Ad Absurdum

i

i.

ϕ

A

⋮

ii.

ψ

Goal

⋮

iii.

~ψ

Goal

iv.

~ϕ

RAA: i, ii, iii

Forward

Enter the negation you wish to add.
Cite what it negates and two contradictory lines.
Hit Return

Preview shown for the Typed Forward Strict derivation type in the LRC system