No, it does not mean that. A finite amount of time can still be all the time there is, with NO “before” or “nothing” anyhere or ever. One might as well say that the universe has always existed, ie. it is eternal.
If we’re taking “eternal” to mean “non-temporal”, then I think my statement is correct. If we take it to mean “existed for all time” then you have a point, but I don’t think that the square demands that definition of eternal, Sentient Meat. Welcome back, by the way. 
Yes, this odd word “eternal” certainly requires some clarification. I’d also like to explore what you mean by “non-temporal” (ie. timeless?)
I offer that **there is no difference between a state of timelessness and an amount of time (infinite or finite) without change, and that both might describe the singularity (or near-singularity) which lies about 14 billion years “away” from this “place” called 20/7/2004.
Nobody seriously proposes that there was ever a state of nothingness.
Which is why, of course, we are not on that position of the square, yes?
Actually, I’m still unsure where modern cosmology is on the square, which seems altogether to simplistic when we are discussing the nature of time itself.
Perhaps the important question is “is time temporal or eternal?”
I’d answer “both”.
Given your own perspective on metaphysics, I’d say that is probably the right answer for you, and that you should likely reject any conception of “eternal” that suggested anything else. It still seems to me, though, that we’re not in the top-right position of the square, regardless.
No, I’d guess “Some is eternal” is probably the informed choice - the “some” being spacetime, which can have different temporary arrrangements (just like atoms were once thought to be eternal but their arrangements temporary).
The argument needs no formal refutation because there is no logic at all to its conclusion. Whether anything is eternal or not has no bearing at all on whether anything has meaning.
If no finite amount of something can be meaningful, then an infinate amount cannot be meaningful either.
0 to the power of infinity is still zero.
All this time I’ve thought the meaning comment was in addition to the argument, which was about which part or parts of the square we must be on. Sort of a Randian, “… and that is all according to self-evident reason. If you disagree, you’re an irrational, evil,Communist moocher.” If the argument is actually just about meaning, then I won’t give it another thought, as I think several philosophers have given great treatments on meaning that are partially or totally incompatible with each other yet are about as well supported, and none of them have to do with whether or not anything exists eternally.
That was my interpretation as well, although it is an obnoxious and damn stupid thing for a philosophy professor to say in a lecture. Unless perhaps she was trying to goad them into challenging her claims instead of just writing down whatever she says in their notebooks. I could imagine some of the philosophy professors I’ve known being tempted into doing that.
Thank you. And you’re right, the whole thing assumes that something cannot come from nothing, a claim that I’m not convinced of either. I sort of forgot about this as I became more focused on how her conclusions depend on assumptions about the nature of time.
Quantum physics pretty much tosses this proposition overboard. Methinks the instructor needs to start reading some more up-to-date material (or to stop being intimidated by it).
erislover, I feel like we’re both repeating ourselves, but somehow failing to understand each other. Perhaps this argument will prove something is eternal by its own duration. (Although I guess it would only be “half-eternal”, since it had a beginning.)
At any rate, I think the debate between us has gotten a little off topic for this thread, so I’ve created at new thread in case you want to continue the debate. I’ve limited the new thread to the points on which I think we really disagree (see below).
But that assumes there was a “first existent.” Which there doesn’t need to be if time extends back infinitely. It’s like saying “the first integer.” They extend forever in both directions, so there is no first one.
I guess that depends on what field you’re in. In physics, the beginning of time generally refers to the Big Bang, when all of space and time expanded from a single point. But there wasn’t nothing at the beginning of time, there was a singularity. (I’m not sure how well known the term singularity is to those without physics training. For anyone who doesn’t know: It’s the same thing you find at the center of a black hole.)
Incidently, that may be part of our communication problem here. Most of my education is in physics and math, and if yours is something else (philosophy, for example) we may be using the same terms to mean different things.
I am conceding the point that time itself would have to be eternal if it extends back infinitely. If I appeared to dispute this point before, I apologize, it is obvious that If time extends forever then it is eternal. One doesn’t need an ellaborate proof to see that. I think where we disagree is not on this point, but on this business of something coming from nothing (more on that in a moment).
Yes, when I was considering the case where it extends back infinitely, then it was my assumption. However, that is just one possible case, as I said, I think it is more standard (in physics) to think it doesn’t extend back infinitely. My point in saying it was an assumption was not to say that you’re wrong. My point was that the original poster’s instructor’s argument doesn’t prove anything non-trivial. If you assume time extends forever, then something (time) has been around forever. If you assume time started 15 billion years ago, then everything has only been around for 15 billion years. This isn’t profound.
This is what I disagree about. I don’t think something could have come from nothing unless there was a point in time at which there was nothing.
I guess that using “temporal” as you have defined it it is correct to say I feel that all is temporal, and time had a beginning. I don’t think this means it “came from nothing”, because that suggests there was some “time before time” at which there was nothing. Thus, I think that even if it is impossible for something to come from nothing, this doesn’t disprove the claim that all is temporal.
I’m pretty much broke (metaphorically speaking) too, but let me try to simplify things:
SUMMARY:
(1) I don’t disagree with the claim that if time extended back forever, then something (namely time itself) is eternal. I won’t read back over everything I wrote, but if I made statements that appeared to dispute this claim, consider them retracted. I will say that a proof such as the one the original poster’s instructor gives is not required to prove that something is eternal in this case, as it’s an assumption about the nature of time.
(2) I do disagree with the reasoning that if you have an infinite chain of existents, then the “first existent” came from nothing. I don’t think there needs to be a first existent. (Consider, for instance, my example with integers.)
(3) Yes, if you have an infinite chain of existents extending back forever in time, then time is eternal (since it extends back forever). I’m not disputing that conclusion, I’m just saying you can’t prove it with an argument that the “first existent” needs to come from somewhere, because there doesn’t need to be a “first existent.”
(4) I don’t think that in the case where time began a finite number of years in the past it is correct to say it came from nothing. That suggests there was a “time before time” where there was nothing. I consider “a time before time” to be a meaningless statement.
SUMMARY OF SUMMARY:
I think there are only two main points on which we possibly disagree:
(1) An infinite sequence of existents extending back into the past need not have a “first existent.”
(2) Just because time began at some point doesn’t mean it came from nothing. That implies there was a “time before time” with nothing, and you can’t have a “time before time”.
Perhaps (2) all boils down to a difference in what we mean by “came from nothing.” If you consider anything that starts at a certain time to have “come from nothing”, regardless of whether there was actually a previous time at which there was nothing, then your statement that if time had a starting point then it came from nothing is correct. However, I think that if you are choosing this broad a definition for “came from nothing”, then there really is no reason to think that something couldn’t have come from nothing. (Not that there necessarily is reason to think that anyway.)
At any rate, if you have more comments, particularly on these two points, I suggest you use my new thread so we don’t totally sidetrack the discussion in this one.
By the way, I have enjoyed reading what you’ve written on this topic, despite the fact that we haven’t been able to reach a consensus.
Addressed in the other thread.
Well, profundity is where you find it. Asking where things come from has plauged most of mankind since we have written words.
Yes, a point in time. That speaks volumes about the position you’re taking. Notice the top right portion of the square indicates that “everything is temporal”. This is why I keep suggesting that’s where you’re sitting.
Quite so… including “no time”.
I think it says exactly that.
Everyone disagrees with this, so far as I know, so I think you’re safe. 
I’ve addressed the integer notion in the other thread.
No, there doesn’t need to be, but if we suggest otherwise, then we are left with a different conclusion… one you also seem to be against.
I don’t think it suggests that there was a time before time. In fact I think it suggests there was nothing.
I wish I wouldn’t have mentioned this part. No matter how many times it has been explained by myself and other posters it seems like half the people reading the thread are still hanging on it.
Correct me if I’m wrong, but all that was meant by this whole business of things having no meaning was If you reject the validity of logical reasoning then nothing has any meaning. This was mentioned because the whole argument hinges on the assumption that logical reasoning actually works, and this was an attempt to justify the use of logic. I doubt any SDMB poster doubts the validity of logic (although I might be surprised), so there’s no point in debating this bit about things “having no meaning.”
So yeah, you’d probably have spared yourself a headache by not bringing it up.
I think that this is either incorrect, or you are privvy to some new information about QM. I don’t believe virtual particles allow us to state that something comes from nothing, if that’s what you’re referring to.
Exactly. Thank you for understanding.
I’ll reply in the other thread. I just wanted to add that I’m not saying that the question of where things come from is not profound – I just meant that I don’t think the chain of reasoning outlined by the OP really adds anything significant to the discussion. At least nothing that wasn’t clear to begin with. Ultimately either something can come from nothing or it can’t. If things can’t come from nothing, then there must have been something to start with.
I would find it more profound if the argument actually showed that one of those two possibilities must be true. But it doesn’t. It just throws away the possibility of things coming from nothing, and concludes that the other choice is true. But yes, the question of where things come from is a profound one, in my opinion.
(Incidently, if it seems surprising that I’m now saying either a thing can come from nothing or it can’t, when before I seemed to argue for a third possibility, it’s because I’ve realized that the way you and I have been using the phrase “comes from nothing” isn’t quite the same. I’ll mention this when I post in the other thread.)
I guess it’s a question of what “counts” as something coming from nothing. If something comes from nothing and then returns to nothing before it can be observed, does this count? If something comes from nothing, but then is only able to stick around long enough to be observed because it borrows energy from something real (i.e. non-virtual), then can we still say it came from nothing?
What can be said definitively (I think) is that things can happen at random, for no reason – at least no reason other than the fact that the laws of physics allow them to happen and predict that they will happen a certain percentage of the time. But I don’t think that’s quite the same as something coming from nothing.
One example I like is the structure of the universe, which supposedly is due to vacuum fluctuations in the early universe. So the presumably homogeneous early universe produced the inhomogeneous universe we see today. It’s not exactly something from nothing (because there had to be a universe to begin with), but it is structure from total uniformity, which is bizzarre enough in and of itself.