You miss the point, I was asking the commenter to make some rational claim not an appeal to authority, now you repeat that fallacy and add on the fallacy of ancientism-if its ancient it must be wrong.

The problem now is that you are making the mistake found in modern logic generally, namely, that you never get outside the realm of concepts. That is the "game" played by devices such as "quantification" and "instantiation."

But our real knowledge begins in judgments of existence, such as, "Something is there," from which I then abstract concepts about the nature of the subject.

A copula does not have to be formally expressed, since it is merely a sign for the joining of two concepts in the mind, or else, it may be a judgment of existence which is where real knowledge begins.

I am well aware of the claim by modern logicians that existence is not a first-order predicate. The problem is that we do know things exist and from this form a concept of being from which we get the principle of non-contradiction.

This is how we actually enter the realm of metaphysics. If you want to get tied up in just logic, be my guest.

I just noticed you have about eight different replies to me on this thread, and frankly, I have a life besides this thread. So, I may be brief.

I am well aware of the complexities entailed in building a body of knowledge. We form universal first principles from the concept of being, such as those pertaining to non-contradiction, sufficient reason, causality, finality, and so forth.

The rest of our knowledge must be slowly built by forming universal concepts abstracted from existential judgments of things we actually encounter in experience. Very few such things allow for really universal forms of reasoning. The rest often depend on induction which is typical of natural science, and is why natural science never gives us a truly universal truth.

There isn't room here to do an entire course in epistemology.

You would never even think of the LNC being true unless you first knew that something cannot both be and not be. Otherwise the LNC would simply be a posited fabrication.

Do you disagree with the authority of physics? Do you think that we should deny scientifically verified claims from what is probably the most rigorous field of science simply because they don't agree with ancient metaphysical claims? I'm tempted to say, "No evidence required when we bend the knee to metaphysics!" but that would be unfair to all of the modern philosophers who take physics into account when discussing metaphysics.

The proposition you just gave is simply a false one. It is impossible to have a male barber that shaves every man who does not shave himself. That doesn't violate the LNC.

Unless we knew already that things cannot both be and not be, the nature of judgment would not function at all, since that is the way we form judgments.

This is true, but only because the statement that things cannot both be and not be is a special case of the law of non-contradiction. We cannot judgements if we do not know that no proposition is true and not true, and that every proposition is either true or not true.

"Not" is a concept, but its meaning can only be grasped after you form the concept of being.

I don't know why you think that. I'm not even sure whether to consider "being" a concept at all, since it adds no new information about something to say that it exists. But even if the concept of "not" first requires the concept of "being", the LNC still comes directly from the concept of "not".

No matter the mode of predication or the state of the subject, when the intellect forms an enunciation, it conjoins two concepts using an affirmative or negative copula.

That is incorrect. "I run to the street corner," doesn't have any copula in it. The example I gave previously of, "All swans are white," has a copula, but it is not simply an instance of conjoining two concepts with a copula.

This "conjoining" posits that the content of the predicate is a state of reality or a property of the subject that is really present in the subject or really belongs to the concept of the subject.
The "is not" copula does the reverse.

You are trying way too hard to bootstrap facts about human language into facts about reality. Also, you are misinterpreting the "is not" copula. "X is not Y" is really just a shorthand for "It is not the case that X is Y" that is more convenient due to English grammar. When we say, "X is not Y", we are not predicating the concept "is not Y" of X, at least not usually. For example, when we say, "Bigfoot does not exist," we don't mean that Bigfoot instantiates the concept of nonexistence (that is obviously nonsensical) - we mean that it is not the case that Bigfoot instantiates the concept of existence (since there is no Bigfoot, Bigfoot does not instantiate any concepts).

Using your methodology, you could never learn anything about anything, since all knowledge would be singular in significance.

All I did was deny that you cannot derive universal or logically necessary knowledge from a single experience. That doesn't rule out the ability to know these things in other ways, like logic or induction.

It is only because we can form universal concepts from singular experiences that we can develop a body of knowledge.

As I already said, though, forming a universal concept is not the same thing as knowing a universal truth. I can form the concept of "cat" from my experience, but that doesn't actually give me any information about the external world because simply forming the concept of "cat" doesn't tell me if there actually are any cats, other than the one I just experienced, nor does it tell me any information about these cats if they exist, except what is true by definition.

But you have to distinguish the essential from the accidental,

I already did when I said, "To be absolutely sure about some statement about all cats, you would either have to observe every single cat, or the statement would have to be true by definition."

But it does tell you something already, namely that it is the sort of thing that can have cats in it!

You cannot learn from one cat being inside one house that all houses can have cats in them.

"The mind knows that being cannot be non-being," would not make the LNC logically necessary. Logical necessity does not rely on what anyone's mind happens to know. It can't be derived from direct experience either - I have absolute certainty that I exist - it is immediately evident due to direct experience - but I cannot derive logical necessity from that. In some possible worlds, I would not exist.

You may not be reflecting on this, but it is immediately evident that the same reality cannot both be found in something and not be found in it at the same time.

Of course that's immediately evident. It's immediately evident because denying it would be a contradiction. This is still a logical reason, not a metaphysical one.

Let me put it this way. How do you KNOW that the PNC is "logically necessary?" Is it somehow inherent in its very wording? If so, what about its wording makes it "necessary?"

Haven't I already explained this? It is inherent in its very wording. It is inherent in the very concept of "not". Anyone who claims "P and not-P" either doesn't know what "not" means or doesn't know what "and" means.

If it does not come from immediate grasp of what it means to be and not be, where do you get it from?

You are almost correct there. It does come from the immediate grasp of the meanings of the terms involved. However, the meaning of "being" has nothing to do with it. I don't know why you keep insisting that the concept of "being" is somehow involved when you have not explained any connection between the concept of being and the LNC.