A Problem of Logic

[peter]

All humans are mortal
Socrates is a human
Socrates is mortal

An old chestnut, but one that causes me a problem. Is the logic in fact just circular, self-supporting or does it stack up. Are we making the assumption that Socrates is mortal in fact before our first statement. What if he isn't. All humans have not yet been born and died and what of logic when one doesn't? Why is the statement qualitatively different from the Turkey who on Christmas Eve says

Every day the farmer feeds me
Tomorrow is a day
Tomorrow the farmer will feed me

If this, our most simple forray into the world of what can be known is so fraught with pit falls then what of knowledge? Or isn't it?

[Avatar]

Good one.

Yes, there is an assumption.

No matter how you state it (Socrates is human, all humans are mortal, Socrates is mortal), there is an assumption. We assume humans are mortal in that formulation. It's a fairly safe assumption, but it is still an assumption. And it's deductive of course, not inductive. Just because we have only ever seen white swans, does not mean all swans are white.

I don't know if there is any way around it. If there is no way to know whether certain circumstances pertain, yet we need them to, we have no option but to operate on the assumption that they do.

--A

[Fist and Faith]

Maybe it's not a matter of assumption, but a matter of definition.

[wayfriend]

It's a syllogism.

It should be read this way:

• Major Premise: All humans are mortal.
  Minor Premise: Socrates is human.
  ...
  Conclusion: Socrates is mortal.

Yes, the premises are just that: premises. Givens. A prioris. We assume that they are true.

The conclusion is derived from the premises. And it's inherent in the syllogistical process that the conclusion is valid (correctly derived), but it's only as true as the premises. IF all humans are mortal, and IF Socarates is human, THEN WE MAY BE SURE THAT Socrates is mortal.

Everyone operates on some set of premises. That's part of being human.

• Only God has absolute knowledge.
  Humans are not God.
  Humans do not have absolute knowledge.

There's no problem with logic here that I can see. Logic need only be valid; the responsibility for truth lies in the assumptions.

[Vraith]

Maybe it's not a matter of assumption, but a matter of definition.

Sometimes there are problems of definition, for sure...but that's a different category of problem.

The "problem" is one of the primary reasons for the distinction between "valid" and "true." The Socrates argument isn't circular, it's linear. It is valid, but it may not be true.
I'm pretty sure that all logics have an "implied IF" at the beginning.
One doesn't have to eternally rely on assumptions, in theory [though probably has to start there]. Because those things should be explainable/provable.
For instance ordinary geometry depends on assumptions. Eventually, all those assumptions were proven to be so...though I think for one of them it took a very very long time and, it turns out, by modifying it one can create entirely new, consistent, and useful geometries.

Of course, it is also pretty easy to create [or avoid???] FF's definition problem...sorta...by saying the first claim includes the definition that if a being isn't mortal, it isn't human, no matter what it looks like, if a bird isn't white it isn't really a swan no matter how swan-dentical in every other respect. [in an attempt to make it true, instead of merely valid].
But that's cheating.

Heh...in a way, this is the reverse direction [but same basic form] as your thing that our final equation/total knowledge must account for metaphysics...everything above, that, so this, everything below.

The world is fraught [[or we wouldn't have M.A.D.]] and logic is fraught [[or we would know M.A.D. is INSANE]].
And someone sometime in the last hundred years or so said something like:
"To the extent logic describes reality, it is not consistent. To the extent it is consistent, it does not describe reality."
And knowledge is definitely fraught...it as a field in philosophy all by itself [which you know] there are [I'd guess]at least thousands of books, many billions of words, dedicated to defraughting it---and all failing in one way or another, which causes everyone to fret except those like Hawking who have killed off philosophy in their minds. [[that's right! Philosophy did not die a natural death, it was MURDER!]]

[Fist and Faith]

My position is that it's not a premise, nor a problem. It's a definition. Humans are living beings that live on Earth; have mental characteristics A, B, and C; have physical characteristics X, Y, and Z; are mortal; etc. That's the definition of human. If Socrates is human, and we're told he is, then he's mortal. If it turns out he's immortal, we know whoever told us he was human was wrong.

[Zarathustra]

It's not exactly a definition, FF. "All bachelors are unmarried" is a definition. While "all men are mortal" contains words we've defined, namely, "men" and "mortal," the union of these two, however, is not a priori, but rather an induction built up from observations of every man (so far) in fact dying. You don't have to observe a bachelor to know that he is unmarried; it's contained in the meaning of the term.

So there is a problem with the premise, and it's the problem of induction, pointed out by Hume. We haven't yet seen all humans, so how do we know? Maybe some in the future will be immortal. Of course, we could change our definitions at that point and call that type of man something else, but that doesn't really seem fair for the purposes here.

However, the logic moving through all three statements is sound. If all men are mortal, and if Socrates is a man, then he is indeed mortal. There's no problem with deduction--moving from the general to the specific, or a class to a member of that class. It's the other direction of induction--from the specific to the general--that is logically problematic.

This also applies to predictions of the future, since it assume that the past will always be like the future, an assumption that can only ever be based on the past, therefore contains circular reasoning. That's why the turkey is wrong.

[Vraith]

My position is that it's not a premise, nor a problem. It's a definition. Humans are living beings that live on Earth; have mental characteristics A, B, and C; have physical characteristics X, Y, and Z; are mortal; etc. That's the definition of human. If Socrates is human, and we're told he is, then he's mortal. If it turns out he's immortal, we know whoever told us he was human was wrong.

Yea, I know, but the "problem" part resurfaces...you just dodged it temporarily...
And it can go the other way. [which I was trying to point at in the previous.]
You say "if he's immortal, then whoever said he was human was wrong."
But it is every bit as possible/probable/likely [and problematic] that your definition was wrong. That the definition included the property "mortal," because [and probably ONLY because] no one had yet seen an immortal one.
Differences result---
IF all humans are mortal.
Vs.
GIVEN all humans are mortal.

Definitions may be intended to include, convey what things are.
But they also exclude, convey what things are not.
And BOTH of those things can be wrong.

There is a difference between putting a definition to work/using it for a purpose/making it a tool and claiming the definition is real/factual---heh "definitive."

[wayfriend]

That the definition included the property "mortal," because [and probably ONLY because] no one had yet seen an immortal one.
Differences result---
IF all humans are mortal.
Vs.
GIVEN all humans are mortal.

Those are not actually different phrases at all. They mean exactly the same thing.

What changes is how much we assume the antecedent is factually true.

Also, I will point out to you that all of science is based on GIVENS that have proved true only as far as we can test them, and then we've deduced the hell out of it to get where we are now. No one ever proved that ALL copper conducts electricity, in the sense that we haven't tested ALL copper - and yet the assumption has proven useful. The point being, don't knock assumptions just because they are assumptions. Assumptions are important and useful and valid. ALL "facts" are, in the end, assumptions.

[Fist and Faith]

I know what you guys are saying. I just think you're wrong. I think you're putting the burden of proof on me, when it should be on you. I don't think I have to allow for the possibility of immortality in the definition until you prove the possibility is greater than zero. Otherwise you could insist that I not include "can't fly" in the definition. After all, we haven't seen every human jump off a skyscraper, so we can't know that some of us won't fly if we jump from some minimum height.

[wayfriend]

Perhaps, FnF, it's worth discussing the difference between continent truth and necessary truth.

A truth is necessary if denying this truth leads to a contradiction. E.g. Red is a color.

A truth is contingent if something happens to be true but need not be true. E.g. My car is red.

So: it is a contingent truth that humans cannot fly. The statement "humans can fly" is not inherently a contradiction ... it's just contingently false.

It is a necessary truth that humans are mammals. The statement "humans are not mammals" contradicts the definition of human.

[Orlion]

I know what you guys are saying. I just think you're wrong. I think you're putting the burden of proof on me, when it should be on you. I don't think I have to allow for the possibility of immortality in the definition until you prove the possibility is greater than zero. Otherwise you could insist that I not include "can't fly" in the definition. After all, we haven't seen every human jump off a skyscraper, so we can't know that some of us won't fly if we jump from some minimum height.

This might be a "difference" between logic and reason. Logically, we do not know nor can we know all humans die (unleash we unleash some doomsday device)... reasonably, I would kinda stare at you a bit, say something like, "Really? Do you have one verifiable instance of someone not dying? No? Then feck off!" And stick out my tongue and make fart noises.

Which means: logic is a tool. It's a great tool. But if you do not know how to use it, it's not going to help you.

[Vraith]

What changes is how much we assume the antecedent is factually true.

The point being, don't knock assumptions just because they are assumptions. Assumptions are important and useful and valid. ALL "facts" are, in the end, assumptions.

The first is exactly my point. [and so is most of the second].

And it does make a difference how we treat them.
But "facts" aren't assumptions "in the end."
They are probably assumptions in the beginning...
And may remains so in the process/middle...
But not in the end.
In the end, they're facts in a given context [or contingency, if you prefer]
or facts universally.
Or they're false.
[[hmmm....maybe there's a category/possibility of things "a-factual."---where "factness" is irrelevant. I'll have to think.]]

[Fist and Faith]

Perhaps, FnF, it's worth discussing the difference between continent truth and necessary truth.

A truth is necessary if denying this truth leads to a contradiction. E.g. Red is a color.

A truth is contingent if something happens to be true but need not be true. E.g. My car is red.

So: it is a contingent truth that humans cannot fly. The statement "humans can fly" is not inherently a contradiction ... it's just contingently false.

It is a necessary truth that humans are mammals. The statement "humans are not mammals" contradicts the definition of human.

You're making me think along these lines: We do not say, "He's a mammalian human." It's redundant, or at least obvious, because it's one of the defining characteristics of human. For the same reason, we do not say, "He's a mortal human."

If we found a non-mammalian human, we'd certainly point it out. We would have to, because it goes against the definition. And we would surely say " immortal human" if we found one.

[Fist and Faith]

On the scientific and factual side of things, what do we know about the life processes of any human, or humans in general, that allows for the possibility that there might be an immortal human? The thought: "Just because we haven't observed one to live to the age of 200, survive the removal of his heart, survive being fully immersed in water for an entire day, etc, doesn't mean it is not possible." is not a scientific, fact-based reason to think there might be immortal humans.

[wayfriend]

ALL "facts" are, in the end, assumptions.

But "facts" aren't assumptions "in the end."
They are probably assumptions in the beginning...
And may remains so in the process/middle...
But not in the end.

Well, then that's where we part company. There is no contingent truth you could name, in which "to the best of my knowledge" isn't implied in the statement. This is because humans have no direct access to absolute truth. (And isn't that the kicker that makes the world what it is.)

There is only truth we observe (contingent) and truth we deduce (necessary). Truth we observe is necessarily limited, possibly twisted, and ultimately interpreted. ("All humans are mortal ... as far as I can tell.") But we call them facts anyway. Truth we deduce is not a "fact", but a "definition" - a common agreement, good only where common folk agree. ("All humans are mammals, because I define 'mammals' and 'humans' how I want to.)

If we found a non-mammalian human, we'd certainly point it out.

You could not -ever- find one. A non-mammalian human is a contradiction. It's not a matter of never finding one, it's a matter of such a thing being impossible by our own terms.

And we would surely say " immortal human" if we found one.

Indeed. In fact, it's important to note that we would consider an immortal person a human, while we would not consider a reptilian person a human, nor a fungal person. Again, this is contingent vs necessary. Immortal humans are not impossible, merely improbable.

[Wosbald]

+JMJ+

If this, our most simple forray into the world of what can be known is so fraught with pit falls then what of knowledge? Or isn't it?

I'm not quite sure what's going on in this thread.

If you're questioning the validity of Knowledge, then your question is presupposing (assuming) that which you're trying to prove.

And if that's the case, then maybe you should just go have a few beers and play some Super Mario Bros. until you feel more centered.

[Zarathustra]

"All facts are assumptions" is the same as saying there are no facts. Of course there are facts. You don't have to assume them. There's a process of verification (i.e. observation). Assumptions are things you assume are true without verification, taking it for granted.

We don't just assume copper conducts electricity. We discovered it. Discovery is the opposite of assumption. And transferring this discovery (via induction) to all copper isn't an assumption, it's based on a theory, an explanation, which is tied to more things than just that single piece of copper, but also (for instance) all the myriad observations that led to and subsequently confirmed quantum mechanics. We know how electricity works, and what's happening at the atomic structure. And this same exact theory not only accounts for this piece of copper, but what's happening in the sun and every other star. When you tie divergent facts together like this into an interlocking whole with explanations, they are far from assumptions.

Logical truths are necessary, so it's fair to say that denying it leads to a contradiction. However, "red is a color" is not an example of one. Denying that red is a color only leads to a false claim, not a contradiction. "Red" is only a color because of contingent facts: a) we've named a frequency of electromagnetic radiation this word, and b) our senses, by accident of evolution, happen to detect this frequency. We could have very well detected different frequencies, or named them something else. There's nothing logically necessary about it. It's just a contingent fact.

It is not a necessary truth that humans are mammals. This is also a contingent fact, that arose from many accidental factors, none of which were logically necessary. "Humans are not mammals" doesn't contradict the definition of a human. Humans aren't defined as mammals, they were discovered to be so. Discovering the nature of all the contingent facts which comprise us is not a process of definition, though it is true that we pick the words to match those discoveries. Again, this isn't the same as defining, it's naming. I choose the name "Bob" for my cat, but I haven't defined the word "Bob" in this process. I can choose the word "mammal" for a certain class of animals, but the discovery of that class is not the same as defining a word or concept.

Lots of confused reasoning here. Is there anyone (else) here who has actually studied logic formally?

[Fist and Faith]

We are not more mammalian than we are mortal. Mortality is as much a part of us, is as much the definition of us, as being mammals is. Because our psyches are as big a part of us as our bodies are. (I would argue it's the more important part. I consider things like my: love of Bach; certainty that there is no afterlife, deity, or anything supernatural; hopes, desires, fears - to be more important than things like my: height and weight; top running speed; eyesight.) And our psyches are what they are, to a large degree, because of our mortality. Our certain, even imminent, deaths shape us, individually and as a species, at least as much as anything else does. Wolverine said this to the Beyonder:

YOU SAID YOU WANTED TO LEARN WHAT IT WAS TO BE HUMAN -- BUT HOW CAN YOU, WHEN YOU'RE IMMORTAL? EVERYTHING WE DO -- EVERYTHING WE ARE OR HOPE TO BE -- IS FRAMED BY THE SHADOW OF DEATH.

There was an episode of Highlander with a young woman who was a brilliant musician and composer. She was an immortal who didn't know she was immortal, because she hadn't yet died for the first time. That's how it worked. Heh. They stopped aging when they died the first time. Other immortals could tell if you were immortal, and if you were an immortal who had not yet died for the first time. So one immortal killed the musician, in order to "freeze" her at the height of her musical abilities. But it backfired. Without the knowledge of her own mortality, she lost her musicality. The passion, the drive, the fears, the hopes and triumphs against those fears, were all gone.

This is from The Trial of Billy Jack. (Which is a terrible-terrible movie, unlike Billly Jack, which is a fantastic-terrible movie.)

PROSECUTOR
What you're saying, then, is that it doesn't make any difference to you whether this jury finds you innocent or guilty. That it doesn't make any difference to you whether you live or die. Now, you expect us to believe that you have absolutely no fear of the death penalty?

BILLY JACK
I have a lot of fear. But I have a lot more respect. Long ago I learned that he's my constant companion. He eats with me. He walks with me. He even sleeps with me.

PROSECUTOR
I'm sorry. I must have missed something back there. Who is this faithful companion of yours?

BILLY JACK
Death.

PROSECUTOR
Oh, I see. Now tell me, does this, is this death-companion business some special part of your Indian beliefs?

BILLY JACK
No. Every one of us has death as his constant companion. He sits with every one of us every second of our lives, only we're too terrified to really think about that. But once you do, it'll completely change your entire outlook on life.

PROSECUTOR
How so?

BILLY JACK
You ask yourself, even in the most serious crisis: How important would this really be if I were suddenly told that I just have one more week to live. So you learn to take nothing too seriously. On the other hand, you ask yourself: If this were my last act on earth, is this what I really want to do? So you learn on the one hand to be detached from the temporary things of this world; and on the other hand you learn to appreciate every little thing in it all the more.

How many death scenes in literature, tv, and movies are we mesmerized by? Tragic ones. Comic ones. Circle of Life ones. By the hundreds and thousands. Sometimes the death scene is the very reason for the movie. I could go on forever quoting or describing them. By every great and every terrible author and actor. I just gave you a few lesser known ones for variety.

How many beings of power have, upon first meeting us, said, "Greetings, mortal." It's how we - speaking of ourselves through these beings - view ourselves.

Mortality defines us. All life is mortal, but it does not define any other life the same way, to the same degree, that it does us. Because we know we're mortal. And that knowledge is the basis of the way we live more thoroughly than, arguably, anything else.

And, as I said, there is - nothing - whatsoever - about us that suggests there might be any humans who are not mortal. Outside of fantasy/scifi, immortal humans is a contradiction; medically and psychologically.

Now, I didn't go through all that just to discuss mortality. Sure, it's a topic worthy of any number of discussions of any length. I want to make sure I'm being understood when I say mortality is as much the definition of human as mammal is. A different aspect of human, but not an aspect that is less important. Or less certain. Believe it or not, I understand what you're all getting at. What I'm getting at is that logic is flawed if it tells us we do not know that all humans are mortal; if it tells us we do not know Socrates is mortal.

And what happens, wf, when genetic engineering leads to humans who are not mammals? Are they still human? Will we consider them a hybrid? Lizard-men? Will we not think of them as human at all? And what about when genetic engineering leads to humans who are not mortal?

[Obi-Wan Nihilo]

The underlying fact of this entire thread, is that we don't really know all that much about what it means to be either human or mortal.