DeMorgan's laws are used by electricians to plan your household switches. That's useful, no?

Here's the picture that leads to this mistaken view...

Over on one side we have the world, and over on the other side we have logic. Isn't it astonishing that logic somehow just happens to "fit" the world?

But logic and the world are not so distinct.

It's like being astonished that a glove just happens to have five fingers.

How do I get outside of logic to ask about it?
Aren't I using logic to talk about it?
My brain hurts.

Why do you need to get "outside" of logic in order to talk about logic? What could that possibly involve? Indeed, demonstrably, we are here talking logically about logic.

Did I just not ask that question?

You introduced the notion of getting "outside" of logic. If we agree that it was introduced only to be rejected, then all's well.

I thought the OP introduced the idea.
I am not interested in making fun of it. It is the outline of many interesting things.
My question was not rhetorical.

I thought the OP introduced the idea. — Valentinus

Where does the OP introduce "getting outside of logic"?

Again, the notion of logic being distinct from the world is misguided.

"Wow, isn't it astonishing that logic just happens to fit the world..."

No; logic was chosen and grown within the world in order to set out how the world is. That's not astonishing.

To ask this:

I guess the main question is what is the nature of logic and how come it is that its nature is so useful to humans? — schopenhauer1

is to look at it as something that is not necessary in every instance. And that point of departure is "outside" of accepting the process as necessary as such.

(...walks away.)

From what?

But logic and the world are not so distinct.

It's like being astonished that a glove just happens to have five fingers. — Banno

But what are you implying here?

How do I get outside of logic to ask about it?
Aren't I using logic to talk about it?
My brain hurts. — Valentinus

What is the implication then?

Its usefulness is a bit mysterious, — schopenhauer1

That's because trying to explain logic, is like asking why 'why' means why. Logic is the basis of explanation, it is not 'what is explained'. If you want to understand logic, you understand how to use it, not why it is applicable or what it is. SO - I endorse Valentinus' response.

We could start in the simple with identity.
Without identity, what would these comments mean?
Indeed, meaning presupposes identity.
That's not to say these comments are all meaningful, but, hey... :)

It's like being astonished that a glove just happens to have five fingers. — Banno

:ok:

It's quite redundant to ask why gloves have five fingers but such an interpretation derives from thinking the world is logical in structure and function. I agree.

All that needs to be kept in mind is that logic can must change according to what new discoveries we make. In fact, according to quantum physics the law of non-contradiction doesn't apply or something like that.

The Laws of Thought are not created. It is certainly a very slippery area to look at because our use of language is so messy and nuanced that the most delicate attempts to be precise end up with convoluted analysis and mistakes.

We’re not exactly the most logical creatures and really have problems dealing with abstract ideas.

The three laws are:

- Law of Identity
- Law of Contradiction
- Law of Excluded Middle

I was referring to the Law of Contradiction in another thread addressing the absurdity of starting from a contradictory position as if it is of use toward claims of truth and/or validity. A trick many mystics use is to lay out a contradiction as a premise or proposition alongside another equally absurd beginning in order to make them appear of value - the dogma being to accept the statement blindly and follow logically from a non-position and thus allowing them to arrive at any conclusion they wish to. It is the endless problem of inference that is also used to bolster such delusions.

A trick many mystics use is to lay out a contradiction as a premise or proposition alongside another equally absurd beginning in order to make them appear of value - the dogma being to accept the statement blindly and follow logically from a non-position and thus allowing them to arrive at any conclusion they wish to. It is the endless problem of inference that is also used to bolster such delusions. — I like sushi

The mystic roosts his argument in absolute truth, the scientist roots his argument in empirical and universal truth, while the post-modern philosopher, that's you, roots his argument in contradictions and opinions such as "there are no absolute truths," which is either absolute true or not true, or it is true sometimes, in which case there are absolute truths. if it is absolutely true that there are no absolute truths, there is an absolute truth and a contradiction ensues. And if it isn't absolutely true that there are no absolute truths, then it is universally or relatively true that there are no absolute truths and the potential for absolute truths to exist is still possible. So, what in the f*ck are you talking about?

I guess the main question is what is the nature of logic and how come it is that its nature is so useful to humans? — schopenhauer1

As an example, there are infinitely many possible syllogisms, 256 distinct forms, 24 of which are considered valid in traditional logic, and 15 in modern logic.

What a logician calls logic are just those forms or patterns that are deemed useful for certain purposes in the space of all possible forms and patterns. Understood this way, it's not mysterious that we distinguish patterns that help us achieve our purposes from those that don't.

What a logician calls logic are just those forms or patterns that are deemed useful for certain purposes in the space of all possible forms and patterns. Understood this way, it's not mysterious that we distinguish patterns that help us achieve our purposes from those that don't. — Andrew M

This is sort of going in the direction I trying to go. idea here is also leaning in that direction to. are looking in that direction.

I notice most of the answers here have to do with logic's place as already useful. I find it interesting that an inquiry on the nature or origin of logic is almost considered impossible. What is the implication of that then? Well, you can just say, "It's foundatioanal", and "it is what it is", but how unphilosophical is that? Here we have a set of tools that we use in the world to create other tools, but we don't and refuse to look at it closely?

Is logic something that the universe provides? Are we divining/discovering logic? If so, is logic just how the universe operates? If so, is this different than the idea that we are divining/discovering math? Is that the same thing being that math is also an ordering/pattern principle? Is it more foundational or less foundational then math then as it might underride math (pace early Bertrand Russell).

If math is simply something that is nominal- we make it up to help make sense of the world, why can it be used so effectively in things like generating outputs from inputs? If put to use in a technological context, it is the basis for modern engineering, science, and technology.

What is the implication of that then? Well, you can just say, "It's foundational", and "it is what it is", but how unphilosophical is that? — schopenhauer1

I think it’s a mistake to think that maths or logic is something that can be explained. The same goes for scientific laws. All of these are the constituents of rational explanation, not things that themselves can be explained. And it’s not unphilosophical in the least to recognise that, it's simply an acknowledgement of the nature of knowledge.

You can’t ask why the law of identity holds, or why elementary arithmetic proofs are valid. They are the basis on which judgements of validity are made. The issue that I think you're grappling with, is that there's a tendency in analytical philosophy to believe that there's a naturalist explanation for such elements - but all such accounts are circular in my view. Why? Because:

How do I get outside of logic to ask about it? — Valentinus

Say you try an explain logic in terms of neurology, of what the brain does (which is the stance of brain-mind identity theorists). You're obviously not going to see the elements of logic in literal neurological data. What you might be able to do, is infer something about the way the brain processes sensory data and follows rules - but as we all know, it's an extremely complicated matter involving many levels of abstraction. But in that kind of analysis, you're already utilizing the very thing you're wishing to explain. Logic (etc) are internal to the act of thinking. So you can't stand outside of it, and see how it works; you only understand how it works by using it, by applying logic. But you don't get to turn around and see its source. (That is the reflexivity problem of the 'eye not seeing itself'.)

I read a great quote earlier this week - 'The ‘world’ of experience is not given in experience: it is constructed by thought from the data of sense.’ C. I. Lewis (Mind and the World Order: Outline of a Theory of Knowledge, p29). And that is why maths is predictive - because it helps us to order and predict experience. But maths is not given in experience - again, it is constitutive of the rational operations of the mind. But because of naturalism, we're (usually unconsciously) seeing it in terms of the world 'out there' and the mind 'in here'. And that is the basic root of the problem - we instinctively believe it is (like everything) a result or consequence of evolutionary processes, that it's something that evolves. But the theory of evolution, or any other theory, already depends on logic, as it is built throughout on rational inference. We use it, and take it for granted as something we can explain, but actually, we can't explain it; it is the basis of explanation, not the subject of it.

So it needs to be understood that logic is not so much explained by naturalism, as what naturalism draws on, in order to explain; but that in so doing, it's actually not explaining itself. Once that is understood, a myriad of problems of modern philosophy are dissolved.

Logic is the capacity of consciousness to relate two or more ideas at once, it seems to me.

We get our percepts from the world, and then we order them, build concepts, theories, models, which we then apply back to the world from which they derived (making predictions mostly I guess), sometimes successfully and sometimes not. I don't think it is logic that fits the world, because logic says nothing about the world. Logic is our ability to relate and order what the world gives us.

Logic is essentially about relationships - differences considered together. Validity, for example, cannot apply to one premise, you have to have at least two and to relate them simultaneously to perceive if the conclusion follows.

People who ask this kind of question tend to forget - or are rather completely unfamiliar with - just how much junk math and junk logic are out there. Math and logic that, were one to attempt to 'apply' it to the world, would be both completely useless or utterly wrong. In fact the majority of math and logic is like this, and its only a tiny sliver that, only after arduous efforts of fine tuning and trial and error, ever gets used at all. Part of the problem is that very few people who like to talk about this stuff actually study either, and all they hear about are the success.

It's as if one were to tune into the radio and remark that, based on your extensive sampling of radio, there seem to be alot of musical acts worthy of getting played on the radio. But of course you don't hear about the failures - precisely because they are failures. And math and logic is full of utter rubbish which we disregard for the same reasons. @Andrew M's point speaks to this quite nicely.

I’m reading Logical Investigations by Husserl, at the moment. He is asking these kinds of questions. It’s been a bit of a slog initially, but I’m making some headway now.

Husserl focuses on refutations of psychologism. Maybe that would be an area where you could focus some attention? I’m only one third through the book and plan to start reading Naming and Necessity soon too in order to, hopefully, compliment it.

I’ve never called myself a philosopher. In one sense I guess I’m an ‘amateur philosopher’ in the sense of “philosopher” as one who has studied the texts of philosophers. Post modernist? Not at all.

You still don’t seem to understand that distinction between “fact” and “truth”. Science doesn’t deal in “truths” unless you’re framing ‘logic’ as a ‘science’ - which is fair enough. Mysticism isn’t based in logic so it doesn’t have a higher claim to ‘truth’ over logic. Nothing, by definition, does.

So, what in the f*ck are you talking about?

Take it up in the appropriate thread.

this kind of question — StreetlightX

What kind of question is it? You've clearly perceived this as an example of something general, and I'm interested in that general category.

Questions about the so-called 'efficacy' of formal systems of inference mongering I suppose.

Oh, that specific. Do you come across a lot of such questions?

The math behind any engineering is obviously based on some sort of logic. What then is this logic? — schopenhauer1

This is Boolean logic, and it has little application to humans or to human life except when we want to consider digital electronics. If you mean to refer to logic in a wider sense, then this answer is unhelpful, and I apologise. :smile:

Boolean logic allows us to design networks of logic gates, and thereby to design computers, and the like. Pretty boring stuff, unless (like me) you spent your professional life designing digital hardware and firmware. :wink: Then it can be fascinating!