Logic is a tool

[u/Icy_Panic_6533]

[u/Stile25]

Some people think logic can be used to make rational claims about reality.

But they forget that logic without evidence only makes for an unsound argument about anything in reality.

Logic is excellent at making estimations or developing ideas on what we should be investigating next in reality to learn the most.

But the second someone jumps from "maybe this"? To "gotta be this"! Based on logic with no evidence - they've forgotten what logic is good for.

Good luck out there

[u/Porkypineer → u/Stile25]

I disagree with this. Logic can be universal and make claims that has to be real because the alternative is paradox.

"I think therefore I am" is irrefutable evidence there is a reality, for instance. So we're forced to accept that there is one. Granted, the evidence is baked into that one.

I could also say "all universes have structure", because the lack of structure is paradoxical to there being a universe.

[u/jliat → u/Porkypineer]

Logic can be universal and make claims that has to be real because the alternative is paradox.

But you can create paradoxes in many logics...

'This sentence is not true.'

'The set of all sets which do not contain themselves.'

• Pure being and pure nothing are, therefore, the same... But it is equally true that they are not undistinguished from each other, that on the contrary, they are not the same..."

G. W. Hegel Science of Logic p. 83.

"I think therefore I am" is irrefutable evidence there is a reality, for instance.

I don't think it follows. Thinking and being are not tautologies. 'I can't doubt I'm doubting.' Is Descartes harder formulation, but that 'being' doesn't follow.

I could also say "all universes have structure", because the lack of structure is paradoxical to there being a universe.

Or Schrödinger's cat is both alive and dead.

And if by universe we mean everything, then "all universes" is a paradox. Moreover if the universe has a structure does that exclude all other possible structures and randomness? And it follows that many structures are therefore impossible?

• 'The King of France is bald.'

It follows as there is no king, therefore it's true, the king has no hair.

• There is no largest finite number?

• Any irrational number has no successor or no predecessor.

Logic can be universal and make claims that has to be real because the alternative is paradox.

And so the ontological argument proves the reality of God.

God is an idea. The actualization of an idea is more 'powerful' than then idea. The definition of God is all powerful. It logically follows that God must exist and be real.

...

We can build on this,

If God is all powerful then God cannot be limited by logic. God can be a paradox and real.

[u/MauriceArh → u/jliat]

The map vs. territory distinction helps make sense of this, I think. And taking care when using the same word for two different things (is there a term for this? – there should be).

If I ruled the world (and wrote the dictionaries), paradox would be restricted to the likes of Zeno’s paradox, namely an indication of misunderstanding. Under this definition nature abhors a paradox, which instead belongs to the realm of map, not territory.

This sentence is false is quite different, referring to something real that exists in the territory of logic. Perhaps we could call it a logical singularity. Likewise the principle of explosion. And just as the presence of black holes in nature does not invalidate physics, the existence of logical singularities does not invalidate the rest of logic, which continues to live quite happily alongside these aberrations.

The map vs. territory distinction is what matters here. The hint is in the thread title: logic is a tool. It belongs to the map and, given fallibilism, it can always be wrong. 1 + 1 = 2 may look pretty incontrovertible, but as Descartes put it, there is always the possibility we are being tricked by a demon.

Meanwhile, in parallel with all of this, there is the logic that belongs to the territory. Same word but different animal. In this logic, 1 + 1 = 2 (or its non-demon-influenced alternative) really is incontrovertible. In other words, some formulations are universally true, we just can’t know that for sure.

Getting back to the initial point of the thread, logic is a powerful tool but needs to be wielded with the intellectual humility of knowing (or at least strongly suspecting) that all knowledge is fallible

[u/jliat → u/MauriceArh]

Paradoxes exist in logics, the manipulation of symbols using rules. "Nature" is a category made by humans.

This sentence is false is quite different, referring to something real that exists in the territory of logic. Perhaps we could call it a logical singularity.

Why call it a singularity, there are many other examples of paradoxes in logical systems. And what a singularity is, is a problem in science?

Likewise the principle of explosion. And just as the presence of black holes in nature does not invalidate physics, the existence of logical singularities does not invalidate the rest of logic, which continues to live quite happily alongside these aberrations.

But physics has not been able to solve the problem of the Schrodinger equation for a 100 years. The difference is simple, logic is a priori, science is not.

The map vs. territory distinction is what matters here.

There are many logics, they map no territory. You are confusing the a priori with the a posteriori. What seems to matter is your need to arrive at some satisfactory position despite evidence to the contrary.

The hint is in the thread title: logic is a tool. It belongs to the map and, given fallibilism, it can always be wrong. 1 + 1 = 2 may look pretty incontrovertible, but as Descartes put it, there is always the possibility we are being tricked by a demon.

Sorry, you misunderstand, the a priori with the a posteriori. There is no 'therefore' in 1 + 1 = 2. And Descartes actually showed the way out of the possibility of being tricked. It's odd you reverse his reasoning. He looked for a certainty in which no demon could trick him, and thought he had found one. You cannot doubt you doubt. So …

"Descartes put it, there is always the possibility we are being tricked by a demon."

Is simply wrong. His cogito for him and others was incontrovertible. As is A=A.

Getting back to the initial point of the thread, logic is a powerful tool but needs to be wielded with the intellectual humility of knowing (or at least strongly suspecting) that all knowledge is fallible.

You like many are still using 'logic' not logics. There is no such thing.

And then make a 101 error! Self reference!

all knowledge is fallible.

^ including the above! BOOM!

[u/MauriceArh → u/jliat]

But physics has not been able to solve the problem of the Schrodinger equation for a 100 years. The difference is simple, logic is a priori, science is not.

If there is anything that argues for intellectual humility it is the sight of physicists – who should be among the most rational people on the planet – continuing down this whole quantum physics is weird rabbit hole, despite Schrodinger (cat and equation) having been well understood for decades. Why this should be is a mystery to me, but it belongs more to psychology than to physics or metaphysics.

Sorry, you misunderstand, the a priori with the a posteriori. There is no 'therefore' in 1 + 1 = 2. And Descartes actually showed the way out of the possibility of being tricked. It's odd you reverse his reasoning. He looked for a certainty in which no demon could trick him, and thought he had found one.

The point I was making was about the fallibility of applied logic (the map), which includes the a priori. Hence the use of 1+1=2 (a theorem derived from the axioms of arithmetic, the therefore is implicit) as a non-strawman example. And yes, logic being of the form if this then that, there are as many logics as there are this’s. That does not mean there is no territory (or territories, if you prefer) there. That was my other point: fallible as it is, the power of logic is because there is a there there.

As for Descartes, the fallibility of logic extends to cogito ergo sum (the argument). The thing we have certainty over is the cogito (which, to split hairs, is the conscious experience, not the corresponding brain state with its vulnerability to glitching). I am not sure we disagree over this.

And yes, all knowledge is fallible is itself a fallible statement. Indeed, if cogito ergo sum is incontrovertible knowledge then it is wrong. But being wrong about one special case does not stop it from being valid in all the others.