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On 9/8/2024 11:39 AM, Ross Finlayson wrote:The, "Fixx"On 09/07/2024 07:29 PM, Ross Finlayson wrote:>On 09/07/2024 05:29 PM, Jim Burns wrote:On 9/7/2024 3:13 PM, Ross Finlayson wrote:>Aristotle has both _prior_ and _posterior_ analytics.>So, when you give him>
a perfectly good syllogism with which he disagrees,
he has either of prior or posterior to deconstruct
either posterior or prior,
Wikipedia seems to say that
syllogisms are prior, and
use of syllogisms is posterior.
>
They don't seem to be 'either.or', but 'both.and'.>So, being constructive, constructive criticism,
when I look at the outcome of
otherwise a proof by contradiction to be rejected,
that a "strongly constructivist" view requires that
it's immaterial the order of the introduction of
any stipulations,
where
in the usual syllogism's proof by contradiction,
whatever non-logical term is introduced last
sort of wins,
when
if the terms are discovered and evaluated
in an arbitrary order,
it's arbitrary which decides and which is decided.
Formally
(which is what I think 'by prior analysis' means),
a proof by contradiction only shows that
_one of_ our assumptions is false.
>
However,
of those assumptions,
some are better supported than others.
This is when posterior analysis enters the ring.
>
Consider Boolos's ST
⎛ ∃{}
⎜ ∃z = x∪{y}
⎝ extensionality
>
Those are assumptions.
They are very un.challenging assumptions,
but that is why we select them as starters.
I am currently engaging in posterior analysis, I think.
>
We can follow those with a list of _definitions_
which describe natural and rational numbers
in the language of ST.
⎛ 0 := {}
⎜ k+1 := k∪{k}
⎜ ℕ(k) :⇔
⎜ (k = 0 ∨ k ∋ 0) ∧
⎜ (∀j ∈ k+1: (∃i ∈ j: i+1=j) ⇔ j≠0)
⎝ ...
>
Definitions aren't assumptions.
They are more like public service announcements,
informing "the public"
⎛ let us say: the phone.booth.sized crowd
⎝ which reads my posts
what it means when I write 'foo'.
>
I'm not sure whether definitions stand
with prior or posterior analysis.
>
There is a very strong assumption that
I mean that which I say I mean,
an assumption which does not extend to
an assumption that
that which I mean is correct, or even makes sense.
>
Then there are assumptions made
for the purpose of 'proving' contradictions,
and thereby being themselves disproved.
⎛ √2 ∈ ℚ
⎝ ...
>
Assume √2 ∈ ℚ
Prove a contradiction.
Thereby prove that _one of_
⎛ ∃{}
⎜ ∃z = x∪{y}
⎜ extensionality
⎝ √2 ∈ ℚ
is false.
>
But the first three assumptions, ST, are
very un.challenging assumptions -- by design.
Is ∃{} false, or is √2 ∈ ℚ false?
Is ∃z = x∪{y} false, or is √2 ∈ ℚ false?
Is extensionality false, or is √2 ∈ ℚ false?
>
Posterior analysis(?) suggests √2 ∈ ℚ is false.
It is not as bullet.proof as prior analysis(?),
but it is damn good.
>Then,>
that Russell's retro-thesis is
simply not a fact, logically, [...]
What do you mean by "Russell's retro-thesis"?
>
Yes, I know about
Russell's "set" of all non.self.membered sets.
It would be helpful if you (RF) simply stated,
without embroidery, your own stance
with regard to Russell's "set".
>
>
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