I think that it depends on what one is looking for in a definition. Aristotle famously characterized human beings as rational animals. (Of course, if other rational animals were discovered, it would follow from Aristotle's definition that they, too are human beings. So perhaps Aristotle's definition could be modified to constitute simply a definition of 'person' or 'agent': in which case the discovery of other rational beings than human beings would simply lead to the class of persons or agents being enlarged. For what it's worth, such a characterization would accord with Locke's discussion of personal identity in the Essay Concerning Human Understanding, where he distinguishes between the identity conditions of human beings and those of persons: the latter are such that beings other than human beings could fall within the scope of the concept, whereas the former is limited to human beings, that is, beings that look like human beings and manifest the form of life shared by other human beings.) Perhaps the best definition of a human being that could be given today, however, would be one that involved the genetic make-up of human beings, which differentiates them from other, even closely related species, yet captures what it is to be the kind of creature that belongs to the genus homo sapiens. Such a characterization is, I think, preferable to one that takes human beings to be automata, because other animals could be and indeed have been--by Descartes, for example--characterized as automata. (Although it should be noted that Descartes himself took this characterization to mark a difference between human beings and other animals, since he believed that whereas animals were mere automata, machines, human beings were composites of mind and body, which served to differentiate human beings from other animals, who, according to Descartes, lacked minds.)
This is a version of the question of whether universals exist, about which there has been considerable philosophical discussion over the past 2500 years or so. Some philosophers--call them 'nominalists'--believe that the only things that exist are particulars: in the case of animals, then, only particular sloths, rabbits, dogs, etc. exist; some philosophers--call them 'realists'--believe that not only particulars, but kinds, or universals--in the case of animals, the kind 'sloth' or 'dog' or even 'animal' itself, distinct from particular instantiations of that kind--exist. (Some realists even believe that kinds or universals are the only real things, and that particulars aren't real, or at least not real in the same respect that universals are real.) It seems to me that where one stands with respect to the universalist/nominalist divide may in part reflect one's account of cognition, or how one comes to know things: if one believes that the senses are the only source of knowledge, then one may be inclined to think that only particulars exist, and that universals are abstractions formed on the basis of a consideration of particulars (such a position was taken by John Locke in the Essay Concerning Human Understanding, where he said that kinds or sorts are "the workmanship of the understanding"); if, on the other hand, one thinks that in addition to the senses, human beings have the capacity to cognize the essences of things, then one will be inclined to think that universals exist. Further pressure towards one position or the other may come from whether one thinks that nature is, as it were, 'carved at the joints', or whether whatever carving is done is either done by human beings or happens over time, as, in the case of animals, in accordance with the dynamics of evolution. For one might think that if species--kinds or categories--themselves evolve or change, then they aren't real, because they are subject to change; alternatively, however, one might think that even though species may indeed change over time, there is more to a species than its particular members. So do categories or universals exist? I think one's answer to this question is shaped by the kinds of epistemological and metaphysical commitments that one is prepared to make, and what tradeoffs one is prepared to make if one does or doesn't make such commitments. To wit, if one doesn't believe that categories or universals exist, then one needs to give an account of how we come to use categorical or universal terms, and also to what those terms refer when one uses them; if one does believe that categories or universals exist, then, while one can easily explain the meaning and reference of categorical or universal terms, one will need to give an account of the nature of those universals, how we come to cognize them, how their existence is related to that of particulars. I think that there is much to be said on both sides: for what it's worth, I myself am not sure what I think--perhaps some other panelist has a firmer view on the matter.
Kids do ask some amazing questions.
I am no expert on child psychology. I am just a philosopher who is also a parent. So please do not take what I will say the wrong way. I do not really mean to be giving parenting advice here.
To some extent, what you should tell your son depends upon your religious beliefs. Some traditions would hold that your son was with God, waiting to be embodied. Some would hold that your son may have had a prior life, about which you would not know very much. But I am guessing that none of these traditions is yours, since otherwise the answer to the question would be clear enough. So I will answer assuming that you believe that, prior to your son's birth, he did not exist. (Note that many religious traditions would hold this view. So this is not a religious vs non-religious issue.)
So, telling your son the truth would mean saying something like this:
We can make cookies, but before we make the cookies, there aren't any cookies. There is flour and butter and sprinkles, but they have to be made into cookies. Before we make the cookies, they aren't anywhere, are they?
Well, Mommy and Daddy made you, but before we made you, there was no you. So no, you were not alone, just like the cookies are not alone before we make them. And like with the cookies, before we made you, the stuff that we made you from was already there. Part of you was already in Mommy (the ovum), and part of you was already in Daddy. [OK, that's not really true if we go far enough back, but let's not be pedantic.] And then we made you, and we sure are glad we did!
I think something like that would be comprehensible to a four year old, and I'd be fascinated to hear how the discussion would continue. But you will have to judge if you think your child is ready for this kind of thing.
It's odd, by the way, how the idea of nothingness after death is so much more terrifying than the idea of nothingness before birth.
You clearly hang out with interesting people. These issues are much discussed amongst proponents/critics of various forms of 'telological' or 'design' arguments. You can find in Aquinas the idea that if time stretches back to infinity then eventually every logically possible outcome occurs, which he uses to argue that not every existing being exists contingently, at least one exists necessarily. You see the response (eg in Hume against Paley's biological design argument) that for all we know the alleged design in nature occurred via a very long series of random permutations, some of which are bound to be ordered, and obviously any one which includes us would be an ordered one so there's certainty that if we are doing the investigation we shall discover the order -- Nietzsche famously argued for the 'eternal recurrence' suggesting that an infinite time not only does everything happen but that it happens over and over again an infinite amount of time ... but you're raising the question in terms of probabilities and certainties -- which is strong langauge -- if Aquinas/Nietzsche are right, this very conversation is itself an eventual certainty to occur -- but does that make it any less amazing, meaningful, reason to base beilef in (say) a designing God on? Hm.
I believe that your question is a good one, and that there is a further one that it suggests. The further question is where the dust particles might have come from. Or if we mean by "the universe" absolutely everything, including dust particles, then the universe did not come from a few dust particles or anything else, as, if it did, then the universe came from a part of itself, which is clearly impossible.
I'm with Thomas Pogge on what the real issue is here. For what it's worth, I'm also no friend to the Ontological Argument. But let's see if a supporter of the argument might have something to say in response to this challenge...
First of all, what form of the argument are we going to consider? It's been presented in many different ways over the centuries, and some versions have had much more force to them than others. In its simplest form, the argument basically goes as follows. God, by definition, possesses every perfection; existence is a perfection; therefore, God possesses it, i.e. God exists. But this version is notoriously vulnerable to objections like those that, for instance, Kant formulated way back in the eighteenth century.
But there are other versions. One of the best (particularly associated with Leibniz, but formulated by several other people too, both before him and since) basically goes like this. (i) God, by definition, possesses every perfection; (ii) necessary existence is a perfection; (iii) it is possible that a God, thus defined, should exist. Therefore, God does exist. Given a few extremely basic principles of modal logic, it can now be shown that the argument is valid, in the sense that the conclusion really does follow from the premises. How does this work? Well, to say that it is possible that God should exist is equivalent to saying that there is some possible world or other where God does exist. Thus far, this possible world may or may not be the one that we actually inhabit. But we can still consider what will be true at such a possible world, even if it isn't actual. And, given the other two premises, one thing that we can declare to be true at that world is that God necessarily exists. But to say that it is true at a certain possible world that something necessarily exists is equivalent to saying that it is true at every other world that it exists. And our world is certainly going to be among these others. So it is true at our world that God exists. Indeed, from this it follows in turn that God necessarily exists here. So there you have it: the Ontological Argument is logically valid! Sound the trumpets!
But, of course, validity isn't everything. What we really want is 'soundness'. It's not enough for the conclusion to follow logically from the premises: we also hope that the premises themselves might actually be true (and, indeed, that we might have solid grounds to believe them to be true), for only then will we have any solid grounds to accept the conclusion.
So let's now look more narrowly at the 'dirty fingernails' argument that you've raised. The place where a defender of the divine argument is most likely to criticise your reformulation of it will be on the possibility of the existence of the being that you've defined. People like Leibniz went to some lengths (albeit with questionable results) to argue that the perfections they attributed to God were all 'compossible', i.e. that it was possible that a being should have all of them together. And I think this would be how they'd respond to you: they'd deny the compossibility of dirty fingernails with the perfection of necessary existence. No being, they would say, could have both; i.e. they would reject your version of premise (iii). And, since the argument hangs on the interaction between the necessary existence described in premise (ii) and the possible existence described in premise (iii), they would thereby declare that your version of the argument was unsound.
And why might dirty fingernails be regarded as incompossible with necessary existence? Well, plenty of reasons. If we don't reject that compossibility, then we do indeed seem to be facing a very real prospect of being forced to accept the necessary existence of the being you've described. But that would mean that these dirty fingernails themselves necessarily exist, and that just doesn't seem right. Can't we imagine possible worlds where no fingernails exist at all? Moreover, if this alleged being's dirty fingernails are anything like the kinds of fingernails that we are familiar with -- and, if they're not, then why are we calling them 'fingernails' at all? -- then they ought to be every bit as destructible as any other fingernails are. But destructibility and necessary existence definitely don't seem to be compossible. So the being you've described (all-perfections-plus-dirty-fingernails) doesn't seem to be a possible existent; i.e. there is no possible world where such a being exists; and consequently the 'necessary existence at some world' step in the argument, and the move from that to existence in the actual world (and from that back to necessary existence in the actual world), never actually kicks in at all.
great point -- I think I largely agree -- but there may, still, be some disanalogy between the two cases (the Irish legend v. 'God') -- namely once you begin describing God's various attributes (omnipotence, creator, goodness, etc.) then it may well be plausible to seek independent/direct evidence of his existence in the world around you, independent that is of the 'source' of the 'tale' itself -- and that might not be equally true, or true to the same degree, as in the Irish legend case -- after all, you may not need to know who thought of the idea of a 'Creator' God first in order to evaluate, perfectly rationally, whether the world around us exhibits any evidence of intelligent design or creation -- of course, when you do learn more about the 'source' of the idea of God that may increase your skepticism about the truth of the claim that God exists, but it does seem to me that claim may also be evaluable independently of its sources --
I am not a vegetarian but I think I should be. I would not couch the issue in rights language but putting animals through suffering just so I can have my New York Strip Steak just seems wrong to me. Given human history, I cannot imagine what kind of arguments we humans could muster if aliens came down and proposed to us as a food source.
The medieval philosophers used to think of existence in terms of degrees, and some in modern philosophy entertained such an idea (Kant, for example, described God as the most real being). but usually existence is not treated as something that comes in kinds or degrees or in different senses. Actually, some philosophers seek to avoid the term 'exists' unless really pressed upon. So, for example, a philosopher might think it less misleading to say that Dumbledor is a character in Rowlings' novels rather than to say that Dumbledor exists in Rowlings' novels.
There are, however, two areas when 'existence' as a term / concept gets a bit tricky: some theologians believe that to claim 'God exists' is to treat God as simply one of any number of things that exist. Some of them, therefore, prefer simply to refer to God without the word 'exist' or 'existence' (e.g. affirming there is a God of love rather than claiming there exists a God of love). One philosopher in the last century speculated about whether there may be objects that neither exist or do not exist; he thought some things may subsist.
Yes, we do think that things exist which we cannot pick up or see. (For instance, we say that numbers exist, or that the center of mass of the solar system does.) What precisely do we mean by "exists" then? That's one problem you raise. I'm not sure how to answer it: the notion of "existence" seems so basic, it's hard to imagine much light being shed on it from other, yet clearer, notions.
But you raise another question: whether there's something problematic in even asking what "exists" means. Your thought is that there is, since the question itself involves the notion of existence. I'm not sure that it does: In asking for clarification of a notion, we're not asking whether that notion exists (whatever that means). You might say that we're asking what "exists" means. And although it's not clear exactly what we're doing when we ask what a word means, it doesn't seem right to say that we're asking whether something exists.
Of course, your paradox could perhaps be reinstated by shifting our focus to the word "means". What does "means" mean, you might now ask. Here you might argue as follows: either we know what "means" means, in which case, there's no point in asking this question; or we don't know what "means" means, in which case we don't even understand the question. In sum, if we understand the original question then there's no point in asking it. This issue has been kicking around since Plato's day! It's sometimes known as the paradox of analysis. You can find some information about it here.