Is logic 'out there' or is it invented?

In case this sounds naiive, perhaps I should start by saying I am a novice in philosophical matters. I am trying to decide whether ‘reason’ (i.e. the rules by which we argue) is something empirical that we have discovered, rather than something that is socially constructed. I am asking this because, when arguing some point, I am often faced with assertions such as ‘oh, that’s just your logic…’, as if the rules of inference and deduction are something we humans have invented. My own intuition is that although ‘logic’ is something invented, logic is just a formalism of something that is out there and independent of humans.

I’m sure this is something that must have been thought about but I don’t know where to look. I have seen a quote from Descartes, which says ‘Whether I am awake or asleep, two and three added together are five…’, which seems like it might be about such issues, but I don’t know the context of the quote. Most of what I have read seems to assume that the rules of reasoning are simply taken for granted. I wonder if this is because they are self-evidently universal, and that this needs no justification.

Can anyone help me out?

There is the definitional, relative, understood logic and there is the ideal, absolute, and known logic. The first is what we work with and the second is what we strive for. It’s like beauty: there is what we see in the real world with all it’s limitations, but there is also the ideal upon which the real is based. So the answer to your question is “both.” Definitional logic is understood but not known. Ideal logic is known but not understood. As we “progress” (I hate that word) we move from the former to the latter but get no closer to anything. As we move forward, shit falls off the back and we forget about it. It becomes more shit we still know but no longer understand.

Why does there have to be an “absolute beauty” or “absolute logic”. Both are formal concepts that allows for a discourse on the subjective nature of both “beauty” and “logic” but I’m not sure that those absolutes exist as anything other than empty definitions.

Logic a technique for exposing the relations between statements - statements that are prelogically (inductively) assigned a truth value.

Anything that can be called a technique is manmade. We can discover new logical relations, but that brings us no closer to any ultimate truth. The truth is in our statements - or it’s not. Logic exposes analytical truths only. Any introductory text on logic will probably cover this. It’s not a mystery.

I don’t know about that Faust. There seems to be a lot of confusion regarding that here. People will say that humans aren’t logical, presenting “logic” as some “other” that is “out there” as opposed to a product of the human mind.

What you’re asking, basically, is whether Platonism is true or not. The idea that reason and logic have an independent existence “out there” - that is, outside the human mind - was Plato’s.

This has fallen out of favor now-a-days (but many still hold onto it), and it is generally understood that reason and logic are intertwined with human thinking.

It’s like CharlieGadfly said - there are two kinds of logic (and I don’t know if these are the two he had in mind but…): folk logic and formal logic. Folk logic is probably what your friends are talking about when they say “that’s your logic” - it’s not really logic proper, it’s more like their beliefs and the reasoning they bring to bear on those beliefs. As folk logic, this reasoning is often sloppy and not well thought out. To really think in accordance with formal logic, you have to put in a fair degree of effort - questioning yourself, thinking of alternative arguments, thinking of exceptions, etc.

In either case, however, logic is not “out there” - it is in the head. Folk logic can vary from one person to another whereas formal logic cannot. If we all thought formally, we would all think the same (ideally), but this doesn’t make it any less in-the-head than if we thought divergently.

I think you answered your own question. There doesn’t “have to be” anything. But there is; whether conceptual aids or empty definitions.

Well that is important then, because your post has it backwards. The ideal is based on the real, it is a tool for understanding the real. Not the reverse as you presented it.

yeah, Xun - it’s surely a mystery around here. But not among those who have studied even rudimentary logic - honestly, at least. It’s the incessant urge to the metaphysical that confuses so many. As gib has pointed out.

What so many don’t seem to understand is that the stuff of logic is language. Which was developed by humans.

Just language - that’s all it’s about.

I disagree. While it is important, it is not important in this argument. The ideal is what we know and will eventually come to understand. Once we come to understand it, the ideal will be yet again further out, known but not yet understood. In otherwords, the ideal IS real; we just don’t understand it yet. The fact that we know it makes it real. The fact that we strive to understand it is our struggle.

As someone’s sig line says (paraphrased) “all that can be imagined, is or will be.” I personally think it is, now, but for our argument here, that matters naught. It is or will be. And we know it. We just don’t understand it yet.

And we all know how falable language and humans are. Therein lies the incentive to to press on.

I remember the first two fundamental principles of rudimentary logic that I was taught (right or wrong, you’ll have to take it up with my prof): 1. You cannot have “A” and “Not A” in the same place at the same time; and, 2. To start an argument, attack the premise.

Take #2 to #1 and place the burden upon the proponent, #1, and he falters mightily. Especially when the theory of relativity crashes into the quantum physics. It seems there are times and places where the laws of physics AND logic break down. But I don’t think so. It think there are only times and places where our falable language, humanity and understanding of physics and logic break down.

Charlie - it’s not so much that language is “fallible” - it’s that we have no way of assigning truth values with complete certainty - we only have induction. That is not the province of logic, however. Logic begins after the truth values of statements, or propositions, are already assigned. I think there is a general confusion here between form (logic) and content (truth).

Your prof ain’t so good at logic. There are more fundamental tenets (axioms) in logic than that A cannot equal ~A. And attacking "the " premise may be a waste of time (deductive arguments have more than one premise). If a deductive argument is not valid, the truth of the premises means nothing. Your prof was taking about formal rhetoric, perhaps.

Keep going. That’s why I’m here (that prof was 1981 :smiley: ).

You say “Logic begins after the truth values of statements, or propositions, are already assigned.” But what distinguishes a “truth value of statements” or “propositions” from a “premise”? And who does the assigning, and how? Is not the burden of proof upon the assigner? And would not a good place to start an argument be at the place where a “truth value of statements” or “propositions” are being assigned? And are not the assigners “humans” using “language”? And how can attacking the premise be a waste of time if the premise is in dispute? What other fundamental principles of logic are there, beyond the “A” thing?

I abhor putting words in peoples mouths, so correct me if I am wrong, be it seems you are talking about “systems.” And, granted, once a system is stipulated to, we work within the system. But it also seems that what you are saying is that logic is relative and not absolute. If this is the case (which I don’t know if that is what you are saying) then what distinguishes the system of logic from the form of logic?

My prof may very well have been talking about formal rhetoric, but it was an intro course on logic (Irving M. Copi, (sp?)) and I’m not sure I see the difference. The rhetoric, after all, brings us back to humans and language struggling with a system.

Gosh, this is all very esoteric and I’m struggling hard to find it helpful! I think this bit helps:

I don’t know if I’m understanding the context in which you used it, but this is the sort of thing I had in mind when I asked my question. It seems to me that this (what I quoted from you) must be true (with all the usual reservations about ‘truth’), regardless of whether humans talk about it or study it formally.

That’s why I used ‘reason’ rather than ‘logic’ (okay, I know I used logic in the thread title, but I was trying to be succint!) Is logic not a formal way to scrutinise and manipulate something else? The ‘something else’ being somehow natural? I am thinking of the ‘you can’t have A and NOT A at the same time’ example someone else posted.

But what puzzles me is that we (humans) argue and reason in many different contexts, but we all seem to share a tacit assumption that we’re arguing on the same terms - or, specifically, using the same rules. This suggests that there’s a consensus, at least outside of philosophy debates, on what the rules are.

My brain hurts again. But yes, there is a system and it is a whole lot more fun to play if you play by the rules. However, some moron like Newton, Einstien, Hawking, etc. always comes along and refuses to play.

The singularity really bugs me and I wish it would just go away.


Charlie - premises (statements - same thing) are either true or false. They can be indeterminate, but then they are of no use in logic - that’s just a bit simplified, but I can’t write an entire text here. Truth or falsity is a property of a statement.

We do the assigning. You and I may not agree on the assignation of truth to a given statement. That’s life. If I say “All men are mortal” and you just don’t agree (this is either a difference in induction or in definition), then my argument isn’t going to have much traction with you, no matter what. But deductive arguments are always really saying “IF the premises are true, THEN…” So, the validity of an argument is not dependent on the truth of the premises. But we do need agreement on their truth to accept the conclusion as true.

Burden of proof is a non-issue. Arguments ARE proofs. Burden of proof is a psychological issue, or a “political” one. I know that statement is controversial - but the actual burden is irrelevant. Agreement is reached or it is not. Logic is not concerned with the rhetorical quality of the actual debate two people may have. Burden of proof is extra-logical.

We need to distinguish between two senses of the word “argument”. In logic, it is not an undertaking that occurs between two people. Logical arguments - or proofs, begin after the truth value is assigned. A formal argument is executed by one entity - one logician. The “argument” betwen that logician and another is another thing altogether - let’s call that the “debate”. “Argument”, in logic, is a technical term, and should not evoke images of the Academy, with idle rich young men conversing. A logical argument is not a conversation. It is a series of premises, and a conclusion.

There is, on this very board, a beginner’s guide to logic. I haven’t looked at it in a while, but I did help to write it. But this information can be Googled, I am sure. I’ll try to find an accessible list.

Attacking the premise is a waste of time if the argument is invalid, because the argument is invalid. There can be a lot of dispute about the truth of a statement, but validity, or the lack thereof, is simply a matter of following the rules of deduction, of which there are only a handful - the exact number varies according to logicians, because some are really variants of other rules.

Logic is a system, I suppose. It is a set of rules - it is mathematics. Call that a system. But logic is a very specific thing, in philosophy. It is not really debatable. Unless 1 + 1 = 2 is debatable. Many here have debated that very equation. It’s a waste of time.

Logic is neither relative nor absolute. Again, those are terms that can be sensically assigned to truth, but not to logic. You are once again confusing the two. It is a closed system. I don’t know what you mean by “system” and “form”. Logic is a method.

I used Copi in school. Rhetoric is aimed at winning a debate. Logic is aimed at exposing some statements as being contained within others. Logic says “To say A, B, and C is to say D”.

mark- Logic describes the relations between statements. It doesn’t “manipulate” anything. Does mathematics “manipulate” numbers? If it does, then logic manipulates (verbal) statements. Okay, fine.

If there is a way in which you would like to distinguish “reason” and “logic”, please do so. They are often synonyms, but sometimes they are not. That’s just usage.

  1. The Law of Identity, i.e. P is the totality of P, or P is the totality of itself.

  2. The Law of Noncontradiction, i.e. P and ~P cannot both be at the same spatio-temporal instant.

  3. The Law of the Excluded Middle, i.e. P is true [or] ~P is true.

  4. The Law of Sufficient Reason, i.e. P, there exists a sufficient, causal explanation for why P is the case.

  5. The Law of Indiscernibles; i.e. P and Q share all common predicates, thus A and B are identical.

  6. The Law of Bivalence, i.e. P is true or P is false.

The laws of logic do not describe how the world is, that is, the truth of reality. They dictate how truths stand next to each other. There are certain laws which are not contestable, such as the law of identity.

Laws, in effect, become constants because of their non-refutable nature given the context of an argument. Certain laws, such as 6, fold under argumentative contexts. But the laws should be sufficiently understood as coincidental conventions that bear the possibility of refutation, that is, they are not transcendent or “out there.” If the world could be different from what it is, then the laws would still hold. But it is not because they exist in a higher category from the world, they only establish how entities within the world relate to one another. The laws of logic are not descriptive beyond their relational establishment; they will never tell you the truth of a proposition.

There exist many logics which maintain unique rules which define how truth will hold, such as modal or temporal logic, under certain contexts. But if you wish to ascertain a truth-in-itself, the laws of logic and the tool of propositional logic will not do that for you. It will only govern the way you must reason in order to display the truth as it properly should be displayed.

Faust and DeSpinozist:

Both your posts makes sense, and they are how I have actually understood things to be. I don’t quite understand how they are in opposition to anything I’ve said. Quite simply, we have a system which can be turned on itself. To the extent that is merely us doing the turning, and not the system itself, goes to the relative/human/language issue. To the extent it turns on itself independent of us, well, that speaks for itself.

Regarding the numerical equation, any analytical, critical mind would first ask: “One what plus one what = two? And what is meant by plus?” When my wife and I got together, we made three.

Therein lies the need for agreement upon the premise before proceeding, within or without of a system. And burdens of proof are importaint when trying to determine the truth of a premise or when trying to define the system itself. That system is relative and not absolute when we do the defining.

In otherwords, “if” is the confession of flawed tool. Doesn’t mean you can’t use it, just that it’s use is limited.