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Saturday, March 03, 2018

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Soluble. In the syllogism form of the premise
A /is/ B
the /is/ is sometimes, such as here, equivocal as to tense.

Either "Socrates /is/ mortal" should read "Socrates /was/ mortal" or else tetrad leg "c" is false.

You're partially right. (C) ought to be rejected. But then what is the correct definition of mortality?

Fill in the blank:

X is mortal iff X is _________________________.

I suspect “Socrates” is being used equivocally in 1 and 2.

No, reference is to one and the same man.

Finding exception-less nontrivial definitions is very difficult and I don't have a candidate, but I think we can approach the concept better than c. at least, by modifying it to avoid many counterexamples.
For instance, in fiction, there are examples of characters who do not grow old (in science, there is also a concept of biological immortality, though of course humans aren't biologically immortal), but can be killed by a number of different weapons. Those characters are metaphysically possible (some of those are, anyway) and they would be mortal even if nothing were to ever kill them. So, I think biological immortality provides possible counterexamples to C (I think there may be more than one usual concept of immortality, but biological immortality isn't one of them).

One way to avoid those counterexamples would be:

c': An agent A is immortal if and only if there is some thing B that can kill A.

In c', "thing" is construed in its broadest sense, so whatever the correct metaphysics is, it applies to any beings, substances, agents, etc. (regardless of how those categories might overlap), as well as groups of more than one of them. Also, B need not be different from A.
I think C' probably can be improved upon, but also, as I mentioned there may be more than one common usages of "mortal" in common speech, and if so, more than one definition would be needed.
For example, can something immortal become mortal? In a sense I think the answer is "yes", because it would make sense to write a fictional story in which an immortal being chooses to give up his immortality, so there probably is a limited sense of "immortal" that is used commonly. But I think there is a stricter sense in which the answer is "no", so if - say - A1 can bring about X, and then some A2 can kill A, then A is not immortal. So, a correct definition would depend on which concept of immortality one is trying to capture.

That aside, I think Christians would likely reject d. (e.g., Lazarus died twice, according to at least most Christian denominations), and while I think d. is actually true, it's not conceptually so, and I'm not sure it's necessarily so.

Hello, Dr. Vallicella. I'm a long time reader, and first time commenter.

I first want to thank you for your blog. Its last day will be a sad day for me and many others. I hope it's a long way off.

Proposition (c) seems to be the culprit. One reason to dislike it is that it gives quick, sophistical answers to difficult and unrelated problems. For example, one could in the following way argue against Growing Block Theory, which is certainly a live option in the metaphysics of time, if (c ) were undeniable:
C. Every man is such that if there is no future time at which he dies, then he is not mortal.
1. Every man is such that If there are no future times, then there are no future times at which he dies.
2. So, every man is such that If there are no future times, he is not mortal.
3. On a growing block theory of time, there are no future times.
4. So, on growing block theory, no man is mortal.
5. Since some men are mortal, growing block theory is false.

I doubt an argument like the above would convince anyone. GBT should not be so easily ruled out, and once again (c) seems to be the weakest premise.

As for solutions, I don't take myself to have one, but I am hoping you will comment on why dropping the restriction on future times from (c) is not a satisfactory solution. Or, if one has, as I do, the intuition that one who easily could die but luckily never happens to do so should still count as mortal, why not drop the restriction to future times and add the possibility operator? Thus, giving : (c*) A man is mortal only if possibly, there is a time at which he dies.

These are the solutions that occur to a layman like myself, and I'd like to know why they probably aren't as clean as I think.

Thank you again for your blog. I learn from it daily.

-G.B.

Maybe: "X is mortal iff (1) X is alive in some moment y & (2) there is a future moment z after y at which X dies" ?

It seems to me it can be inferred from (c) by using additional premise (C.a) :

(C) A man is mortal only if there is a future time at which he dies.
(C.a) If X can die in moment y, then X is alive in moment y
(C1) "X is mortal iff (1) X is alive in some moment y & (2) there is a future moment z after y at which X dies"

(Not too precise, but I think you get the idea.)

Then, I suppose, Socrates death (B) in light of premise (D) disqualified him as a mortal according to definition (C1).

Having said that, I'm not sure about premise (D) (I am thinking of, inter alia, ideas about reincarnation). What justification do we have for it?

Krzysztof,

That's on the right track, I think. The definition has to be tenseless. How about this:

X is mortal iff (i) there is (tenselessly) a time t such that x is biologically alive at t and (ii) there is (tenselessly) a time t* later than t such that x is not biologically alive at t*.

I say 'not alive' rather than 'dead' since an animal in a state of suspended animation is not alive but also not dead.

Angra,

What I am looking for is a definition of mortality as we know it in human and non-human animals and plants and whatever else counts as biologically alive. As a matter of nomological necessity, every living thing is mortal. So I don't consider logical or metaphysical possibilities to be counterexamples. I wouldn't credit an immortal leprechaun as a counterexample.

In particular what we want to capture is the sense in which we humans are mortal.

Suppose I say that a person is mortal iff he is subject to death. That doesn't quite do it. For a person could be subject to death and never die. Angels, for example, are persons who never die, but as contingent creatures they are subject to death: God could annihilate them. (One might wonder how angels, lacking bodies, could be biologically alive.)

>>c': An agent A is mortal if and only if there is some thing B that can kill A.<<

Well, agency ought not be brought into it. I am not much of an agent when in a deep sleep or a comatose patient in a hospital bed.

It is true that a mortal being A can be killed, but it needn't be by a distinct being B. A man can kill himself. I am also wondering whether your definition is circular. The mortal is the killable, but the killable is all and only the mortal.

You raise an interesting question: can something immortal become mortal? The 2nd person of the Trinity is immortal, and indeed immortal in all possible worlds! And yet orthodox Christians believe that the 2nd person became mortal by becoming a man who was not only liable to die, but actually did die!

And if an immortal thing becomes mortal can it do this while remaining immortal? That is what Christians believe but it is paradoxical to put it mildly.

GB,

Thanks for reading and for the very kind words.

You raise an interesting question that hadn't occurred to me. Suppose we adopt a theory of time acc. to which the present and the past are real, but not the future. How then can it be true that "A man is mortal only if there is a future time at which he dies"?

On the GBT the future does not exist. So it is a realm of mere possibilities. Perhaps one could say this: a man is mortal if every possible future is such that it includes a time at which he dies.

>>I am hoping you will comment on why dropping the restriction on future times from (c) is not a satisfactory solution. Or, if one has, as I do, the intuition that one who easily could die but luckily never happens to do so should still count as mortal, why not drop the restriction to future times and add the possibility operator? Thus, giving : (c*) A man is mortal only if possibly, there is a time at which he dies.<<

Well, it seems that mortality is not merely a modal concept, but also a future-oriented temporal concept.

If x is mortal, then, then for any time t at which x exists, x is possibly non-alive at t. Contra Epicurus, my mortality cannot be shoved into the future: I am subject to death at every instant. It is a worm gnamwing at my innards as we speak and making me ontologically insecure. But there has to be more to mortality than this. For my being subject to death is consistent with my never dying. So there is an added conceptual ingredient, namely, that a time will come when I will die. On the GBT, that time does not exist, but it will come to exist.

But now another puzzle rears its ugly head. Is the GBT consistent with the temp. unrestricted law of excluded middle (LEM)? Assume Bivalence: there are exactly two truth values. Then LEM states that every proposition is either true or false. Consider *BV dies on Jan 1, 2028.* By LEM that is either true or false, but it cannot be either on GBT since there is no such time. On the other hand, if LEM is true without temporal restriction, it might be difficult to avoid logical fatalism. (See R. Taylor's argument for this.)

You can see that a number of tricky issues are roiling around here.

Bill,

Alright, so I think cases of biological immortality would count as actual counterexamples to c, at least if they might avoid some death by universe ending so to speak.

While as far as I know more research is needed so this is not certain, there might be some organisms (including some animals) that do not age, and only die when they're killed by something. Those animals are mortal, but they would remain mortal if nothing happens to ever kill them. Now, there is the question of whether it's possible given the laws of our universe that something will in fact remain alive forever. For example, after the Earth is gone, those animals would have to be taken somewhere else, and then the stars would be gone but there are black holes, etc.

So, it seems that the question of whether it's nomologically possible for an animal to live forever is still open, though there are quantum considerations that might change that, but also considerations about whether the universe is finite in size, etc., and I'm not in a position to fully address those questions. What is clear to me is that all animals are mortal, regardless of whether any of them will happen to live forever. For now, I think we should not accept any definitions of mortality that depend on actual future death (tenseless or not), since we do not know whether it's nomologically possible (even if very improbable) that an animal actually will live forever. I don't know whether any human at this point knows the answer: on one hand, it seems it's not known to science whether anything is biologically immortal, but on the other hand, maybe (or maybe not) enough is known about the future of the universe to give an answer.

>>Well, agency ought not be brought into it. I am not much of an agent when in a deep sleep or a comatose patient in a hospital bed. <<
Hmm...I think you're a temporarily disabled agent. Maybe we use the word "agent" slightly differently. I chose "agent" because it was actually broader than the original "man", and didn't want to use something like "organism" because I think if a person's brain is dead (or the relevant parts) the person is dead, even if other parts of the body are kept alive by a machine (for example). But going by your reply, we can fix that problem by substituting "organism" for "agent" in the proposed definition.

>>It is true that a mortal being A can be killed, but it needn't be by a distinct being B. A man can kill himself. <<

Right, but I stipulated that B need not be different from A in c', so that's not a problem.

>> I am also wondering whether your definition is circular.<<

That might or might not be so, as I was trying to capture the meaning of the term, but I'm just not sure I did capture it (maybe the definition can be improved upon, given the issues I raised and others). But I see that you were looking for something else, and I'm afraid I don't have a candidate.

But what we know to be false is supposed to be a sophism , no?
-This powerfull car is at rest ; maybe nobody will drive her again though she is still powerfull : a potentiality does not need a second proof ,especially mortality ! (C is false).ON the other hand :
-When you say : Donald is great ;you do not mean that he could get onto a chair :he is formally great (leibnizian inherence),not potentially;and the Master added : if this principle is false ,then i don't know what is truth any more....As you know for Leibniz a monade can't extinguish , only God can annihilate her.So the sophism could be :while claiming from a potential feature that he behaves like a formal one ,you change the meaning of "mortal",which becomes "(self)extinguishible"(probably a neologism in english too.
Pure logic or leibnizian....only-woops ?!thanks again for your magnificent blog:i have two coffees in the morning : mine..and yours !

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