Re: William T. Parry gets rid of Disjunction introduction

André G. Isaak <[email protected]> Sat, 4 Jul 2026 21:23:44 -0600

Newsgroups	sci.logic,comp.theory,sci.math,comp.ai.philosophy,alt.philosophy
Organization	Christians and Atheists United Against Creeping Agnosticism
Message-ID	<[email protected]>

On 2026-07-04 21:17, olcott wrote:
> On 7/4/2026 8:28 PM, André G. Isaak wrote:
>> Q is a necessary consequence of P
> 
> seems best handled by
> https://en.wikipedia.org/wiki/Relevance_logic
> or Parry's Entailment Logic
> 
> P □ Q
> 0 0 0
> 0 0 0
> 1 0 0
> 1 1 1

That's *not* a valid truth table. It has no entry for P = 0 and Q = 1.

And Parry is working in relevance logic. He doesn't deal with modal 
expressions like 'necessary'.

André

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