But the evidence says probably only with Homo sapiens about 100,000 years ago. — apokrisis
Am I wrong for prioritizing my kid? — RogueAI
What kind of odds would you give to the climate being that way? — RogueAI
If "red" is just in your mind, when you ask for a red pen, how is it that the person you are asking hands you what you want? — Banno
Without Y, what can be said of X? How do you know it exists and what are its properties? — Hanover
We don't say: If Gu{P} |- Q and Gu{P} |- ~Q, then ~P |- G. — TonesInDeepFreeze
Indeed, the "problem" is not with reduction, but with and-elimination. And-elimination has this form
ρ^μ ⊢ρ, or ρ^μ ⊢μ. We can choose which inference to use, but both are quite valid.
We can write RAA as inferring an and-sentence, a conjunct:
ρ,μ ⊢φ^~φ⊢ (ρ→~μ) ^ (μ→~ρ)
(ρ^μ) →φ^~φ⊢ (ρ→~μ) ^ (μ→~ρ)
(fixed error)
...and see that the choice is not in the reductio but in choosing between the conjuncts. — Banno
Ugh. — TonesInDeepFreeze
I'm dumping this: — TonesInDeepFreeze
I see now. — Lionino
You're welcome for that. (Not too very bumptious of me.) — TonesInDeepFreeze
1. (S & ~P) -> (B & ~B) {1}
2. S {2}
3. ~P {3}
4. B & ~B {1,2,3}
5. ~~P {1,2} — TonesInDeepFreeze
With the non-intuitionistic form we can have the sentence on the last line be P. — TonesInDeepFreeze
(1) If Gu{P} |- Q and Gu{P} |- ~Q, then G |- ~P — TonesInDeepFreeze
the husband is a simp if he doesn't go to the football match without her; in the long run, the wife will respect him more for ignoring her ultimatums rather than giving in — 180 Proof
This makes zero sense to you. — Treatid
And that Logical language has a set of axioms that need a set of axioms that need a set of axioms. — Treatid
Technically: it is impossible to define axiomatic mathematics and first order logic. We haven't actually proved they don't exist - just that we cannot say anything meaningful about them. — Treatid
As such, for any given set of axioms we need a set of axioms that uniquely defines how to interpret that set of axioms. — Treatid
For all practical purposes, we can treat them as if they don't exist. The distinction between "can't be described" and "don't exist" is moot. — Treatid
This would be impossible if the contradictory theory was erected on a logical foundation containing the Boolean principle Ex Contradictione Quodlibet ECQ, from a contradiction everything follows. So ECQ has to be abandoned, but fortunetely that proves possible, indeed mathematically straightforward. What remains is a rich field, of novel mathematical applications interesting in their own right, which sidestep the vexing questions of which foundational principles to adopt, by developing contradictions in areas of mathematics such as number theory or analysis which are far from foundations. — SEP's Inconsistent Mathematics
In a parallel with the above remarks on rehabilitating logicism, Meyer argued that these arithmetical theories provide the basis for a revived Hilbert Program. Hilbert’s program was the project of rigorously formalising mathematics and proving its consistency by simple finitary/inductive procedures. It was widely held to have been seriously damaged by Gödel’s Second Incompleteness Theorem, according to which the consistency of arithmetic was unprovable within arithmetic itself. But a consequence of Meyer’s construction was that within his arithmetic R# it was demonstrable by finitary means that whatever contradictions there might happen to be, they could not adversely affect any numerical calculations. Hence Hilbert’s goal of conclusively demonstrating that mathematics is trouble-free proves largely achievable as long as inconsistency-tolerant logics are used.
The arithmetical models used by Meyer and Mortensen later proved to allow inconsistent representation of the truth predicate. They also permit representation of structures beyond natural number arithmetic, such as rings and fields, including their order properties. Axiomatisations were also provided. — SEP's Inconsistent Mathematics
It should be emphasised again that these structures do not in any way challenge or repudiate existing mathematics, but rather extend our conception of what is mathematically possible. This, in turn, sharpens the issue of Mathematical Pluralism; — SEP's Inconsistent Mathematics
Various authors have different versions of mathematical pluralism, but it is something along the lines that incompatible mathematical theories can be equally true. The case for mathematical pluralism rests on the observation that there are different mathematical “universes” in which different, indeed incompatible, mathematical theorems or laws hold. Well-known examples are the incompatibility between classical mathematics and intuitionist mathematics, and the incompatibility between ZF-like universes of sets respectively with, and without, the Axiom of Choice. It seems absurd to say that ZF with Choice is true mathematics and ZF without Choice is false mathematics, if they are both legitimate examples of mathematically well-behaved theories. — SEP's Inconsistent Mathematics
Shapiro’s distinctive position has other ingredients: mathematics as the science of structure, and mathematical pluralism implying logical pluralism (on logical pluralism see also Beall and Restall 2006); but we do not take these up here. — SEP's Inconsistent Mathematics
The primacy of theories fits, too, with the natural observation that the epistemology of mathematics is deductive proof. It is only if one takes as a starting point the primacy of the mathematical object as the truth-maker of theories, that one has to worry about how their objects manage to co-exist. — SEP's Inconsistent Mathematics
I think we've gotten beyond this talk of "objects". We've moved on to "rules", because rules are what formalism takes for granted. — Metaphysician Undercover
formalism takes rules for granted — Metaphysician Undercover
These seem very similar to me, though you seem to have a desire to drive a wedge between platonism and formalism. — Metaphysician Undercover
If rules are supposed to exist in the same way that platonic objects are supposed to exist, then there is no real difference between the two. — Metaphysician Undercover
inclines me to think — Metaphysician Undercover
Then the rules simply "are", just like platonic objects simply "are", and formalism is a form of platonism. — Metaphysician Undercover
Is it possible to formulate it using first-order logic? — javi2541997
So I have no idea how Macedonia was more civilized. — Athena
If the so-called mathematical objects are fictions then they are not really objects, but fictions. — Metaphysician Undercover
And to call them objects would be false by the principles of that ontology. — Metaphysician Undercover
then we need some other ontology to support the reality of rules — Metaphysician Undercover
Then the reality of agreement, convention, needs to be accounted for, and pragmaticism is designed for this purpose. — Metaphysician Undercover
I don't require your courtesy. — TonesInDeepFreeze
You don't have to feel they are needed nor do you have to request them for me to state them. — TonesInDeepFreeze
Or maybe just say:
Laws of thought are the necessary mental conditions for the operation of the mind. — TonesInDeepFreeze
From that definition, it follows that they can't be broken. — TonesInDeepFreeze
So, when a person is utterly irrational, they are still obeying the laws of thought on account of the fact that there are mental conditions necessary for the operation of their mind? — TonesInDeepFreeze
If a mystic experiences contradictions as being true, then he's not breaking the laws of thought? — TonesInDeepFreeze
If one dreams that one's great-grandfather is both alive and dead at the same time, one is not breaking the laws of thought? — TonesInDeepFreeze
He doesn't. — TonesInDeepFreeze
And a fact about minds is that they are often irrational. — TonesInDeepFreeze
Laws of thought are facts of the matter about your mind — Lionino
Let's understand instead 'laws of thought' as the necessary conditions/operations for my/human/any mind. Since they are necessary, they cannot be broken. — Lionino
You're replies don't even come close to a refutation. — TonesInDeepFreeze
In such mental states, people often break the laws of thought. — TonesInDeepFreeze
Definition of what? — TonesInDeepFreeze
It's plain as day — TonesInDeepFreeze
That is not even remotely constant (2) In this instance, I've been in exactly the right place about what was posts was quoted. — TonesInDeepFreeze
So that is saying that laws of logic may only allude to or be based on laws of thought. — TonesInDeepFreeze
the laws of thought require — TonesInDeepFreeze
Your objection to "If ___, then ___" is a doozy! — TonesInDeepFreeze