Re: William T. Parry gets rid of Disjunction introduction

On 7/6/2026 9:45 AM, olcott wrote:
> On 7/6/2026 6:49 AM, Tristan Wibberley wrote:
>> On 26/06/2026 02:32, olcott wrote:
>>> William T. Parry, Entailment Logics
>>> gets rid of Disjunction introduction
>>> to prevent the principle of explosion
>>>
>>> A simple logical matrix and sequent calculus for
>>> Parry’s logic of Analytic Implication
>>>
>>> The main and distinctive feature of PAI (and of the many
>>> systems of analytic implication belonging to its ilk) is
>>> the rejection of the classically valid principle of Addition,
>>> sometimes also referred to as Disjunction Introduction. In
>>> other words, the principle leading from a formula ϕ to a
>>> disjunction of the form ϕ ∨ ψ, where ψ is an arbitrary
>>> formula. Parry blamed on this principle the derivability
>>> of the paradoxes of strict implication—given that it is
>>> famously featured in Lewis’ derivation of an arbitrary
>>> formula ψ from a contradiction of the form ϕ ∧ ¬ϕ.
>>>
>>> https://philarchive.org/archive/SZMASL
>>
>>
>> Is that available elsewhere without requiring that I agree to terms such
>> as this expansive lot of stuff that has nothing to do with reading
>> something that I should expect either is Parry or is no better:
>>
>> https://www.cloudflare.com/privacypolicy/
>>
>>
> 
> I figured out the getting rid of disjunction introduction
> is required by myself. 

But why would you do that when you agreed on the record that it's truth 
preserving?  (see below):


On 6/28/2026 11:56 PM, dbush wrote:
 > On 6/27/2026 11:34 PM, dbush wrote:
 >> On 6/27/2026 11:23 PM, olcott wrote:
 >>> On 6/27/2026 9:02 PM, dbush wrote:
 >>>> On 6/27/2026 9:53 PM, dbush wrote:
 >>>>> On 6/27/2026 9:49 PM, olcott wrote:
 >>>>>> On 6/27/2026 8:42 PM, dbush wrote:
 >>>>>>> On 6/27/2026 9:40 PM, olcott wrote:
 >>>>>>>> On 6/27/2026 8:29 PM, dbush wrote:
 >>>>>>>>> Given that the following natural language statement is true:
 >>>>>>>>>
 >>>>>>>>> --------------------------------------
 >>>>>>>>> Earth is the third planet from the sun.
 >>>>>>>>> --------------------------------------
 >>>>>>>>>
 >>>>>>>>> In the following natural language statement:
 >>>>>>>>>
 >>>>>>>>> --------------------------------------
 >>>>>>>>> At least one of the following statements is true:
 >>>>>>>>> - Earth is the third planet from the sun.
 >>>>>>>>> - <X>
 >>>>>>>>> --------------------------------------
 >>>>
 >>>> Given that <X> is any *truth bearing* natural language statement,
 >>>> does there exist a statement X such that the condition "At least one
 >>>> of the following statements is true" is false?
 >>>>
 >>>
 >>> Head games will be ignored.
 >>>
 >>
 >> Explain in detail how this is a head game.
 >>
 >> Failure to either answer the above question or explain how it is a
 >> head game in your next reply or within one hour of you next post in
 >> this newsgroup will be taken as your official, on-the-record admission
 >> that Disjunction introduction is in fact truth preserving and valid,
 >> and therefore so is the Principle of Explosion.
 >>
 >
 > Let the record show that Peter Olcott made the following post in this
 > newsgroup:
 >
 > On 6/28/2026 10:52 PM, olcott wrote:
 >  > Q also can't bake a birthday cake, this does not make
 >  > Q in any way "incomplete" relative to what it was
 >  > defined to do.
 >  > ...
 >
 > And more that one hour has passed with no attempt to answer the above
 > question or explain why it is a head game.  Therefore, as per the above
 > criteria:
 >
 > Let The Record Show
 >
 > That Peter Olcott
 >
 > Has *Officially* Admitted:
 >
 > That Disjunction introduction is in fact truth preserving and valid, and
 > therefore so is the Principle of Explosion.