What’s the probability that you exist?

Ali Binazir went to a Tedx talk in San Francisco and heard some probabilities being bandied about that he considered dubious:

One of the talks was by Mel Robbins, a riotously funny self-help author and life coach with a syndicated radio show.  In it, she mentioned that scientists calculate the probability of your existing as you, today, at about one in 400 trillion (4×1014).

“That’s a pretty big number,” I thought to myself.  If I had 400 trillion pennies to my name, I could probably retire.

Previously, I had heard the Buddhist version of the probability of ‘this precious incarnation’.  Imagine there was one life preserver thrown somewhere in some ocean and there is exactly one turtle in all of these oceans, swimming underwater somewhere.  The probability that you came about and exist today is the same as that turtle sticking its head out of the water — into the middle of that life preserver.  On one try.

Like a good skeptic, Binazir first calculated the turtle-head-into-life-preserver probability, making due allowances for the area of the world’s oceans and the area of the hole in a life preserver. That turns out to be 1 in 6.82×1014, or about 1 in 700 trillion. Pretty close to the probability-that-you-exist-figure.

But when Binazir calculated the second figure, he found out that Robbins was off. Way off. But Binazir made that calculation, too, which of course involves some ancillary assumptions and calculations. The probability that you’d exist on Earth today includes the probability that your parents would meet 20 years ago, that they’d have a relationship that would result in pregnancy, and of course that the right egg would meet the right sperm.

But it also includes the probability that your parents would also have existed with the genes they have, which means calculating that every one of your ancestors would have reproduced successfully, and that for each pair of them the right egg would have met the right sperm as well.

He comes up with this probability that you’d exist (by “you”, of course, he means those individuals resulting from the concatenation of a sperm and egg genetically to those who formed your zygote:

Probability of your existing at all: 1 in 102,685,000

As a comparison, the number of atoms in the body of an average male (80kg, 175 lb) is 1027.  The number of atoms making up the earth is about 1050.  The number of atoms in the known universe is estimated at 1080.

So what’s the probability of your existing?  It’s the probability of 2 million people getting together – about the population of San Diego – each to play a game of dice with trillion-sided dice. They each roll the dice, and they all come up the exact same number – say, 550,343,279,001.

A miracle is an event so unlikely as to be almost impossible.  By that definition, I’ve just shown that you are a miracle.

Now go forth and feel and act like the miracle that you are.

Well, somebody’s going to point out to me that although the specific genetic “you” who exists is improbable, the probability that some you, that is, some offspring of your lineage that could be reading this piece, is much higher. Others will pick nits and question Binazir’s calculations. (Given that the number of chromosomes is limited, the probability of getting an individual nearly identical to you is higher.)

But the principle is still the same: it shows the fallacy of the anthropic principle—or of Douglas Adams’s self-reflecting puddle.  But it’s still a cool calculation nonetheless. The read probablity that you exist, of course, is 1.

Ali Binazir’s website, Smart ideas for smart living, is here.

h/t: Matthew Cobb


  1. Posted November 11, 2011 at 7:57 am | Permalink

    The fundamental fallacy with this sort of thing is the notion that probability is in the world, not in the state of knowledge of the beholder. I wonder if they sell great big clubs with Bayes’ theorem printed on the business end.

    • Orlando
      Posted November 11, 2011 at 8:38 am | Permalink

      It reminds me of the court cases on TV where the prosecution argues that the odds of another person having the same DNA is several billion to one and therefore not possible.

      Well, by that argument, if the odds of winning a lottery are several billion to one and you win, then you must give up your winnings because the odds are so high it was impossible.

      They confuse improbable with impossible and over long periods of time or with large enough numbers, the very improbable does happen.

      • Dr. I. Needtob Athe
        Posted November 11, 2011 at 11:26 am | Permalink

        It may seem like a nit-pick, but when the odds of something happening are several billion to one, that means it’s extremely likely, not unlikely. If the odds AGAINST something happening are high then that means it’s improbable.

        To put it in mathematical terms, if you subtract one from the reciprocal of the probability that something will happen, you get the odds that it won’t happen.

  2. chance
    Posted November 11, 2011 at 7:58 am | Permalink

    *the REAL probability that you exist (typo in the final sentence there, you can delete this post once you fix it 😮

    • Julien Rousseau
      Posted November 11, 2011 at 4:34 pm | Permalink

      But he must first read your post to correct the typo read for real.

  3. Posted November 11, 2011 at 8:00 am | Permalink

    Well, once you go down that path, it truly becomes meaningless. I mean, now you have to start incorporating all the odds of all the quantum events in all of history that could have altered the outcomes, plus all of the odds of all the butterfly wings flapping….

    I completely agree. The odds of the puddle being the same shape as the hole is exactly one. Nothing else even begins to make sense.



    • Dominic
      Posted November 11, 2011 at 8:04 am | Permalink

      The universe is information. This is why a god makes no sense – it would have to have more information than the universe. Am I along the right lines here?

      • Posted November 11, 2011 at 8:10 am | Permalink

        It’s basic set theory.

        The omnimax gods are indistinguishable from “the set of all sets.” I mean, that’s the whole point of such gods. Yet it was long ago demonstrated that “the set of all sets” is as meaningless a concept as “the largest (prime) number.”

        The best you can do is a pantheist-style equation of “God” with Sagan’s “Cosmos.” But that just leads to confusion, so why bother?



        • Al West
          Posted November 11, 2011 at 10:10 am | Permalink

          I find this argument very strange. What you are saying is this:

          P1 Some things are in principle unknowable.
          P2 Omniscience, the notion of knowing everything, includes knowing things that are in principle unknowable.
          P3 This is incoherent.
          Ergo, there is no god.

          The problem lies in P2. Why does omniscience have to consist of knowing things that are in principle unknowable? How has it come to be that you have defined omniscience to mean the set of all sets? And what makes you think that this principle applies to a deity, which is by definition outside of the laws of the universe?

          I am not a theist, nor a deist, and I think the arguments presented by religionists are wrong. I am an atheist. But your argument is of the same form as those sophistical paradoxes you see online sometimes: “could god create a rock so heavy even he couldn’t lift it?” And those are not good arguments.

          We could just define omniscience to mean “knowing all things that can in principle be known”. That is not destroyed by your argument, especially if it means, for instance, knowing the absolute position and momentum of every particle in the universe from beginning to end, which a being unconstrained by the laws of the universe could ‘know’, whatever it means to know something under those conditions. And that certainly sounds like an attribute a supposed deity would have, even if it can’t count to infinity. It would also enable that deity to have the knowledge to make moral judgements – so your rejection of the notion of omniscience that you have come up with does no damage to the conventional notion of a deity.

          You have attached a strong meaning to the word ‘omniscience’ that enables you to make the a priori judgement that it isn’t coherent. But perhaps you need to read Quine, “Two Dogmas of Empiricism” (yes, I know – philosophy!), to understand why your argument is actually not a good one, and why your a priori rejection of any deity on the grounds of rejecting a strange supposition, wholly linguistic, of Christian theologians is not reasonable.

          There are plenty of excellent arguments against all kinds of deities. Yours is unfortunately not very good.

          • Posted November 11, 2011 at 10:25 am | Permalink

            We could just define omniscience to mean “knowing all things that can in principle be known”.

            In so doing, you destroy the meaning of the word, “omnipotence.”

            I, Ben Goren, cannot in principle know tomorrow’s winning lottery numbers. But because it is impossible for me to know such things, and your definition of “omniscience” excludes that which it is impossible for the individual in question to know, my ignorance of tomorrow’s winning lottery numbers cannot be held against my claim of omniscience.

            I, Ben Goren, cannot in principle know the precise number of C14 atoms in some random rock on some random planet circling some random star in the Andromeda galaxy. This ignorance, too, does not disprove my claim of omniscience (using your definition).

            Continue down the line, and you quickly discover that, everything that I do not know, it is in principle impossible for me to know. I might well be able to learn it at some point in the future, but my current self cannot, in principle, know such things today.

            Therefore, by your definition, I, Ben Goren, am omniscient.

            Once you start making excuses for a god’s inability to perform a miracle, those same excuses must be applied to all other entities as well. And, as soon as you start handing out those get-out-of-jail-free cards to all comers, it becomes apparent that, once again, the properties attributed to the gods are meaningless.

            Besides. Of what point is a miracle if it’s not an instance of the impossible? Jesus didn’t walk on water because it’s something that a space alien with repulsor sandals could do. He did it because nobody can do it. But, if he really walked on water, then it really was possible…and therefore merely impressive, not miraculous.



            • Al West
              Posted November 11, 2011 at 10:36 am | Permalink

              Your point about miracles is a non-sequitur. And you need to revise your definition of “in principle”. You are stating that you cannot in principle know a number of things that you can, in principle, know.

              I, Ben Goren, cannot in principle know tomorrow’s winning lottery numbers.

              Yes, you can in principle know that. In principle. You don’t know it (and if you do, then please let me know asap). But you could, in principle know that. Heisenberg has some good arguments about the nature of time that rest on a notion of “in principle” that you reject. Perhaps you should read his Physics and Philosophy to discover what “in principle” can be taken to mean.

              In so doing, you destroy the meaning of the word, “omnipotence.”

              No – that is only true if you assume that a deity is both omnipotent and omniscient, and while this is certainly the standard formulation, it doesn’t rule out many kinds of deity. It just means that a deity that is omniscient is not also omnipotent, and while that has obvious implications (ie, there is no Christian god) it doesn’t rule out a deity that i) created the universe, ii) knows everything knowable, iii) makes moral judgements about actions based on knowledge of knowable things, and iv) consigns people to hell for transgressing its moral judgements. Apart from the notion that god has the power to rain thunderbolts on your head and give you boils, you’ve left some notion of a deity reasonably intact.

              And I think we already knew that omniscience, omnipotence, etc, are incompatible – hence theodicy! That is the primary problem theologians have (apart from, you know, the utter non-existence of their subject matter). All you’ve done is to restate this problem and say that it is not resolvable. You may be right, but that’s not a revelation, and it’s certainly not the best argument for atheism, I’m afraid.

              • Posted November 11, 2011 at 10:50 am | Permalink

                You can try to bring all the quantum woo into it you like, but I’m sure Heisenberg, were he here, would assure you that nothing he demonstrated would make possible knowledge outside of one’s relativistic light cone. Tomorrow’s lottery numbers are most emphatically outside that cone.

                But never mind that. Permit me to simplify things further.

                The very principle of personal knowledge is that one can only know that which is recorded in one’s brain. The process by which such information is recorded is very well known and limited. Once one eliminates that which has not been recorded (or subsequently forgotten) along with that which has never presented the possibility for being recorded, one is left with the set of that which an individual knows being perfectly congruent with the set of that which an individual can, in principle, know. Therefore, by your definition, because there’s no way in principle that the individual could possibly know anything else, everybody is omniscient.

                And your claim that it’s possible for an individual to be omniscient (using the traditional naïve definition, not your castrated version) but not omnipotent, but not vice-versa, also falls flat. An omnipotent individual could “use his omnipotence” to make himself omniscient. An omniscient individual would know how to make herself omniscient. Indeed, the two properties are indistinguishable.



              • Al West
                Posted November 11, 2011 at 11:07 am | Permalink

                And your claim that it’s possible for an individual to be omniscient (using the traditional naïve definition, not your castrated version) but not omnipotent, but not vice-versa, also falls flat. An omnipotent individual could “use his omnipotence” to make himself omniscient. An omniscient individual would know how to make herself omniscient. Indeed, the two properties are indistinguishable.

                First of all, I didn’t say ‘not vice versa’. Nor did I say that an ‘individual’ could be omniscient. Given the attenuated definition of omniscience that I discussed – one that is still undeniably the property of a ‘deity’ – it is not possible to know how to make yourself omnipotent, because that is in principle unknowable. But even given your strong version of omniscience, it does not follow than an omniscient being would be able to make itself omnipotent. It might actually know how, but knowledge of how to do something doesn’t equal capability to do that thing. It could know how to make itself omnipotent without actually being able to do it. Either way, it doesn’t hold.

                If we define ‘omniscience’ as being ‘knowledge of the position and momentum of every particle in the universe from beginning to end’, which is in principle knowable (ie, it doesn’t turn into knowledge of incoherent things like the largest prime number or the set of all sets), then this is a coherent property, even if it is impossible in the universe (materially, due to recursion). That means that you can’t reject it due to a priori speculation.

                To provide an example of a deity that is not both omniscient and omnipotent, and one that was worshipped for thousands of years by the world’s most powerful empire, I give you Ahura Mazda (or, in Middle Persian, Ohrmazd), benevolent deity of the Zoroastrian religion, state religion of the Achaemenid, Arsacid, and Sasanid empires. Hardly inconsequential!

                Ahura Mazda is supposed to have created the universe; it is supposed to know everything; it is supposed to make moral judgements; but it is not supposed to be omnipotent, because it has no control over ‘evil’ things, which are the domain of Angra Manyu (MP Ahriman).

                There was a religious movement in the Sasanian era to confound this – this was notably after the rise of Christianity. An omnipotent deity was proposed, named Zurvan, who was supposed to have created both Angra Manyu and Ahura Madza. There was a schism, of course. There always is.

                My point is, if that argument is all you have to go on (and I’m sure it’s not, but….), then you couldn’t be a Zurvanite, but you could be a Zoroastrian.

              • Chris V.
                Posted November 11, 2011 at 2:45 pm | Permalink

                Wait what? Omniscient means “all-knowing”, right? You cannot circumscribe that.
                The largest prime is not “unknowable”, it simply does not exist. That’s the answer that your omniscient being would give you. The same with your set-of-all-sets; it is simply recursive. It may cause problems for your garden-variety omnipotent being, but not your omniscient ones.

            • Occam
              Posted November 11, 2011 at 12:46 pm | Permalink

              “I, Ben Goren, cannot in principle know the precise number of C14 atoms in some random rock on some random planet…”

              Small matter of principle indeed, Ben:
              14C-isotopes are only assimilated by carbon-based life forms, and therefore found only in fossilised remains thereof (or of their rejections, such as coprolites) or carbonate deposits, and only down to a detection limit of 10-15 half lives, i.e. 55-75 Ky, after which there is hardly any radiocarbon left.
              Hence, unless carbon-based life forms would have existed whithin that time frame on that random planet around that random star in the Andromeda galaxy, the detectable number of 14C-isotopes on a random “rock” there (organic fossil or piece of carbonate sediment, rather) would be ~zero.
              An omniscient being would have known that 🙂

          • Gabrielle Guichard
            Posted November 11, 2011 at 1:37 pm | Permalink

            (Outside the topic) I wonder how many believers think that what defines a deity is to be “outside of the laws of the universe”. Most think that a god cannot be defined.

            • Posted November 11, 2011 at 1:42 pm | Permalink

              I’m really not convinced they think that far. “Sophisticated theology” is actually a rarity, for all its practitioners hide behind it. Most believers have a very simple theology based on God being the being with the power of magic. God as “undefinable” is a very recent invention, starting when science really started kicking religion’s ass.

            • Tom Dobrzeniecki
              Posted November 12, 2011 at 6:06 am | Permalink

              I didn’t consider your remark “outside the topic”. I was going to make a similar comment regarding God being the “set of all sets” argument being made above.

              I was raised with a lot of religious training (currently an atheist!), so I know that a common faith-based reply to these arguments would indeed be: God is outside the bounds of our limited knowledge of the rules of the universe, and is able to revise those rules if He sees fit.

        • Barbara Knox
          Posted November 11, 2011 at 6:20 pm | Permalink

          It’s basic set theory.

          The omnimax gods are indistinguishable from “the set of all sets.” […] Yet it was long ago demonstrated that “the set of all sets” is [a] meaningless […] concept….

          Actually, there are set theories which do have a “universal set” (a set of all sets, including itself), for example Quine’s New Foundations set theory.

          And many set theories which lack a set of all sets do have a “proper class” of all sets, where “proper classes” are entities larger than “sets”.

      • Torbjorn Larsson, OM
        Posted November 12, 2011 at 2:24 pm | Permalink

        The universe has access to “more information than the universe” contains in Many World Theory – quantum algorithms (QA) employ not yet fully decohered worlds to arrive at results.

        Hence a QA that uses the observable universe would access more information than the universe contains.

        I think Dawkins, as so many times, nailed it – design theory demands that a creator has more information than the created, and the infinite regress of creators is hence absurd twice over (infinite and infinitely demanding).

  4. Posted November 11, 2011 at 8:03 am | Permalink

    Therefore God did it!

    • Posted November 11, 2011 at 8:06 am | Permalink

      Ah, yes — but, if the odds of you and me existing are so mind-boggling astronomical, then the odds of gods existing must be paracosmological, indeed!

      Therefore, the pot of chamomile I’m brewing did it! Praise be to tea!

      Now, I wonder what the odds of that are….


  5. Sajanas
    Posted November 11, 2011 at 8:06 am | Permalink

    Dawkins had a good point in his Magic of Reality, that the odds of dealing all the cards in a deck to 4 people and having each person get all of a suit is spectacularly improbable. But at the same time, getting *any* specific hand is improbable too, given the number of cards and ways they can be arranged. Its just that we find certain patterns to be ‘random’ and certain patterns to be meaningful. The same could be considered with each human being born. Your parents may have limitless numbers of germ cells to recombine, but there is a spectrum of offspring they can produce. You won’t see two blond people producing a black haired child without liberal use of hair dye.

    • Dr. I. Needtob Athe
      Posted November 11, 2011 at 10:24 am | Permalink

      In one of his science articles, Isaac Asimov once illustrated an extreme improbability by referring to all of the molecules of water in the Earth’s oceans coincidentally moving in the same direction at the same time, causing the oceans to jump out of their beds and go into orbit.

  6. Hempenstein
    Posted November 11, 2011 at 8:14 am | Permalink

    There’s a more straightforward calculation that I like much better. The number of possible combinations of the 20 amino acids (those encoded by DNA, or if you wanna be picky, by mRNA) in a 61-residue peptide is 2061 which is approx 1079, the est # atoms in the universe as noted above.

    • Hempenstein
      Posted November 11, 2011 at 2:13 pm | Permalink

      Dammit! 2061 and 1079 are supposed to be 20exp61 and 10exp79. It took my HTML code with sup, /sup inside carats and just discarded it. How does one make superscripts with WordPress?

  7. Posted November 11, 2011 at 8:18 am | Permalink

    But what if the zygote that finally made you had then split to make a pair of identical twins. Which twin would you be?

    • Posted November 11, 2011 at 8:19 am | Permalink

      The other one. Like, duh!



    • Filippo
      Posted November 11, 2011 at 9:24 am | Permalink

      Is it also true that there could be a second split yielding triplets? Which triplet would one be? Which one would have split unseen by the external world? Could the second twin also split, yielding quadruplets?

    • Marella
      Posted November 11, 2011 at 9:57 pm | Permalink


  8. Posted November 11, 2011 at 8:38 am | Permalink

    In the infinite multiverse the calculation of the unlikelihood of my existence has been performed an infinite number of times, but I only knew about this in the infinite number of universes where I exist & was aware of this calculation having been done

    What that might mean ~ I haven’t a clue

  9. Posted November 11, 2011 at 8:58 am | Permalink

    What’s the probability that you exist?

    It depends on what the meaning of “is” is.

  10. Plainfieldrob
    Posted November 11, 2011 at 8:59 am | Permalink

    Hey All – I don’t anyone has posted this yet, but Sean Carroll posted this yesterday on Twitter – http://visual.ly/what-are-odds

    A infographic based on Binazir’s work…excellent stuff!


  11. Posted November 11, 2011 at 9:01 am | Permalink

    I rolled my eyes at Dr. Manhattan’s similar discussion in “Watchmen.” Laplace’s Demon doesn’t have much need for probabilities.

  12. Posted November 11, 2011 at 9:04 am | Permalink

    The probability that I exist is 1, as you correctly point out. Otherwise I would not be here to post this comment.

    The argument and probabilities being proposed show how silly is the probabilistic reasoning that we see coming from ID proponents and from other creationists. But I suppose it also explains part of the appeal of religion. Many people want to think that they are special and are the result of a special design which had them as the intended goal of that design.

  13. Occam
    Posted November 11, 2011 at 9:18 am | Permalink

    The probability that really matters:


    • Diane G.
      Posted November 12, 2011 at 12:15 am | Permalink

      Thanks, hadn’t seen that one.


  14. Posted November 11, 2011 at 9:22 am | Permalink

    Wow! It seems like I probably don’t exists. I had been under the impression that I did; silly me for making such a mistake! I’ll have to console myself with a non-existent beer.

  15. Filippo
    Posted November 11, 2011 at 9:30 am | Permalink

    Please help my statistical/probabilistic incompetence. Seems to me it’s meaningful to talk about the probability of my existence being 1 only before I “pop” into existence. After that, it seems that most certainly there is a certainty, rather than a probability (even if equal to 1), that I exist.

  16. Sastra
    Posted November 11, 2011 at 10:14 am | Permalink

    The Fine Tuning Argument for God has always seemed to me to be one of the weakest and silliest of the arguments. Yet I’ve seen wised and learned atheists spending plenty of time on it, doing calculations and invoking multiple universes — all to get that number down so that the life-allowing properties of the universe becomes less ‘extraordinary’ and therefore more probable.

    Doesn’t the whole argument fail before you even get to the calculations and odds, though? I’m not a statistician, but it may not be a matter of statistics. Mel Robbin’s talk on ‘this precious incarnation’ or whatever helps to highlight why.

    Here’s the basic set-up of the FTA:

    1.) Pick out something that YOU think is special and important — for any reason you want. It could be the life-allowing properties of the universe; it could be life itself; it could be you; it could be the elephant’s trunk; it could be a leaf falling on a particular spot on the sidewalk at 12:05 pm; it could be a single speck of sand on a planet in another galaxy; it could be the speck of sand to the right of that one. Whatever. Select it with reverence.

    2.)Now, going back to the beginning of time (or as far as possible), think of all the things that might have happened to prevent this special, important thing from happening. Consider all the different ways things could have been, for all you know. Invoke the multiverse, if you want, as well as all the quantum events and their clouds of probability.

    3.) Come up with some calculation of the odds against the special, important thing. For the sake of brevity, we could say it’s going to be something perilously close to ‘infinity to the infinity power …minus one.’

    4.) Good. Gape in awe at your discovery: this special, important thing was clearly selected with reverence … by someone. WHO could that someone BE? Who might have picked out something they thought was special and important in advance of what we find after the fact?

    Ummmm… can we look at step 1 and hazard a guess?

    The whole damn process just seems circular to me. It wouldn’t seem to matter what was selected and what the probabilities are or how they are calculated. The results will be the same. The whole weight and purpose and import of Fine Tuning or ‘precious incarnation’ or any other process that looks at the odds and calculates a miracle is in that first step. In an elaborate and unnecessary scenario, something you select is discovered to have been something selected. A=A.

    Am I missing something more critical here?

    • Posted November 11, 2011 at 12:09 pm | Permalink

      No! I said the same thing here.

      “Isn’t the fine tuning argument BS to being with? It’s my understanding that even if the universe is fine-tuned to support life, we are a biased sample because we would have to be alive to think about it. Further, improbable stuff happens all the time, and we don’t even know the prior probability of getting our universe, so our universe is either not improbable, or it is but that doesn’t mean it couldn’t happen.

      In other words, the multiverse hypothesis is completely unnecessary in answering the fine-tuning argument, cause it’s a shit argument.”

      It’s Statistics 101 that stuff with a very low prior probability happens all the time.

    • Diane G.
      Posted November 12, 2011 at 12:20 am | Permalink

      So nice to be corroborated by two who are much smarter than I am. I’ve never seen the sense in wasting time on this so-called argument, for all the reasons you both state so well.

    • Torbjorn Larsson, OM
      Posted November 12, 2011 at 1:30 pm | Permalink

      The Finetuning Argument is a different beast than the Anthropic Argument though. (Which in turn differs from bona fide anthropic principles).

      It can certainly be cast as the general odds-against as you did, which is an Anthropic Argument large number fallacy. But it can specifically ask about finetuning for life, which is a sensible question. (Which again differs from bona fide physics finetuning of models.)

      However then there is also a sensible answer, which turns out to be bad for believers: the likelihood for any form of livable conditions is actually rather high. And in any case the weak anthropic principle, as it applies in such cases of changing parameters, would circumvent any small a priori probabilities.

  17. Dr. I. Needtob Athe
    Posted November 11, 2011 at 10:18 am | Permalink

    “The read (real) probablity (probability) that you exist, of course, is 1.”

    Are you sure? All this talk from Sam Harris and you that we don’t have free will has caused me to wonder if I exist at all.

    • Occam
      Posted November 11, 2011 at 10:29 am | Permalink

      Then who is asking the question?

      • Al West
        Posted November 11, 2011 at 10:41 am | Permalink

        That is question begging.

        It’s actually a reasonable question: do I actually exist? Certainly in ordinary language I do, and so do you, but there are very good arguments for saying that no, I don’t, and neither do you – at least, not in the same way as elementary particles exist. Look up “mereological nihilism” on wiki, for instance, or find Trenton Merricks’ book, Objects and Persons. It is not such a wacky idea that you do not exist, even if it seems it. It is certainly much more reasonable than it sounds, and is not destroyed by begging the question.

        • Posted November 11, 2011 at 10:52 am | Permalink

          It’s actually a reasonable question: do I actually exist?

          No, the question (when not asked in jest) is idiotic in the extreme. Only a philosopher could take it seriously — thereby demonstrating the idiocy that is philosophy.



          • Al West
            Posted November 11, 2011 at 10:59 am | Permalink

            No, it is not “idiotic in the extreme”. Is the you that exists today the same you that existed yesterday, or five minutes ago, or will exist (hopefully) in ten days time, or the same you that was birthed by your mother? I don’t doubt that is a causal connection between all of these states, and that the stuff that made up them all actually does exist, but unless they are all exactly the same thing, you cannot say that “you” exist, because your exact properties, including causal properties, are not always the same. You reduce to a number of parts which are not you – and so you are at most a fleeting composite. That is not ‘existence’ in the same way that a lepton ‘exists’, and so the terms are not interchangeable salva veritate. So we need more terms. Either the lepton can be said to exist, or you can, but not both without considerable ambiguity or even nonsense. Leptons exist; you… supervene? I don’t know. Any term will do.

            But yeah, you’re right. Dismiss it because it’s philosophy, and philosophy, as everyone knows (surely!), is just stupid.

            • Posted November 11, 2011 at 11:13 am | Permalink

              The lepton is also constantly changing — it is always in motion, it might be part of different atomic configurations, and so on.

              Your concern here is an entirely theological one. Yes, theological — it’s only by presuming the existence of an immaterial soul (or its philosophical analogue, the Platonic ideal) that one can even begin to get tripped up by the gnats you’re straining at here with “Do I exist?” That your woo is labeled “philosophy” rather than “religion” doesn’t decrease the bullshit content in the slightest.



              • Al West
                Posted November 11, 2011 at 11:19 am | Permalink

                Ha! I’m not the one proclaiming so readily that ‘I’ exist as a thing irreducible to little parts. You are. You are saying, outright, that you exist. That is the presupposition of someone who believes in an immaterial soul. All I’m trying to do is make the idea of existence reasonable given what is known about the universe. How you have managed to derive the notion that I believe in an immaterial soul from this is beyond my powers – it seems like madness. It is the absolute direct opposite of what I have just said, which is that I probably don’t exist as an independent entity in the universe.

                The lepton is also constantly changing — it is always in motion, it might be part of different atomic configurations, and so on.

                Yes – but the lepton is the part, not the thing composed. That is the difference.

              • Posted November 11, 2011 at 11:51 am | Permalink

                I’m sorry, but you’re making even less sense now.

                I’ve never made any claim that the self is irreducible to little parts, and I laughed at the idiocy of souls in the post you’re replying to. And now you’re declaring that leptons are somehow not “things.”

                Regrettably, every conversation I’ve ever had with a philosophy evangelist quickly deteriorates into such incomprehensible blather. How quickly it degenerates from all-knowing immaterial minds that can’t know what it’s like to forget something and all-powerful ghosts that can’t feel powerless to subatomic particles that apparently now don’t exist, either.

                You’ll excuse me when I categorize all this as yet another religion, closely related to the religion of Theology, and dismiss it as an utter waste of time. Or maybe you won’t excuse me. I really don’t care.



            • Al West
              Posted November 11, 2011 at 12:05 pm | Permalink

              The reason you think I’m making less sense is because you’ve decide to mutilate my points and misunderstand them, seemingly on purpose. Only that could allow for the crazy things you’ve just said.

              Leptons are things – they are elementary particles, and they are irreducible (at least at present). Their properties are constant, especially their causal properties. Leptons exist, unambiguously and without qualification. The same cannot be said for human beings, which have constantly changing properties made up of and reducing to a series of smaller parts with their own properties.

              That is the argument that is being made. Do you see anything in there about souls?

              I don’t, and I have no idea how you managed to come up with that. There are no souls. There are no essences. There are elementary particles in various quantities, arranged in certain ways, with their own properties. Those exist. Everything else… well, it’s somewhat more debatable.

              And I’m not a ‘philosophy evangelist’. The fact remains that you see fit to pontificate on philosophical issues while having the capability at abstract thinking, it seems, of a sponge. Philosophy is not a religion. It isn’t even a thing. It’s just the name for this kind of abstract thinking.

              I note, also, that you haven’t bothered to defend your claim that you unambiguously exist. I assume that is because it would require that you outline your belief in an essence or soul, something that defines who you are without reference to properties or causal states or anything real.

            • DV
              Posted November 11, 2011 at 12:51 pm | Permalink

              “so you are at most a fleeting composite”

              Do composites exist? If yes then you exist. What’s the problem?

              • Al West
                Posted November 11, 2011 at 1:08 pm | Permalink

                First of all, it’s not as simple as that. I stated it too simply. You are not simply one composite: you are a great series of incredibly complex composites, each different from the last in properties, from birth to death. So even if composites, or wholes, can be held to exist, then the issue is still not settled for human beings. If we say that “I exist” because we can accept that some wholes might exist, then we’re jumping the gun. You could be a whole, but in a moment your component parts will be different, and so will the arrangement of those parts. So even if composites ‘exist’, we have a number of composites rather than just one. And to talk about all of these composites, whose causal properties might reduce to their component parts, as being the same thing – hmm, no dice.

                Secondly, if we use the same word, “exist”, for both the irreducible things that make up the whole and the whole itself, then we are being ambiguous.

                Third, the discussion comes down to causal properties. An electron always has the same properties. One electron is interchangeable in every way with another, because the causal properties of electrons are always the same. They are little bits of the universe that do not reduce to other bits, and the properties of things made up of electrons fundamentally reduce to the properties of the electrons (or other elementary particles, etc).

                If there is something with causal properties that are more than the sum of its parts, then we can talk unambiguously about that thing existing.

                Some people have argued that people have causal properties that are more than the sum of their parts while accepting mereological nihilism in every other aspect. This is called partial mereological nihilism. Its chief proponent is Trenton Merricks, IIRC. His book Objects and Persons outlines the idea of mereological nihilism as well as the possibility that consciousness and intention are causal properties that do not reduce to component parts – and that therefore, people can be said to exist, in a sense, albeit not one that allows for personal identity in the way we expect.

                I am on the fence about that. But regardless, it is hardly an easy topic, nor one that can be dismissed out of hand.

              • Filippo
                Posted November 11, 2011 at 2:07 pm | Permalink

                “partial mereological nihilism”

                Consulting my best dictionary (but apparently inadequate, as I do not see “mereology”):

                “mere” – “pure,” “unmixed”

                Related to “merge”?

                So is it “partial, pure nihilism”?

              • Al West
                Posted November 11, 2011 at 2:13 pm | Permalink

                Mereology – μέρος is the root. It means “part”. I believe Lesniewski coined the term. It refers to the study of part/whole relations, and it’s a branch of mathematics as well as a philosophical branch. I suggest consulting wiki – there is doubtless an article on mereology, and probably one on partial mereological nihilism.

                Mereological nihilism is the view that only irreducible parts exist; anything consisting of irreducible parts with no new causal properties is not a thing, and cannot be spoken of as existing. It is a popular view, because it seems to be the most reasonable, but it comes in a few flavours. Partial mereological nihilism is that only a limited number of special things exist beyond their constituent parts. This usually means: humans, or things with intentionality/consciousness/intention, etc.

            • Torbjorn Larsson, OM
              Posted November 12, 2011 at 2:16 pm | Permalink

              and philosophy, as everyone knows (surely!), is just stupid.

              It is certainly stupid to be able to validly claim that “you exist” and “you exist not” and not being able to decide which it is, not now but never. Join the religious club, but don’t try to make it out as about science and empirical probability.

        • Dr. I. Needtob Athe
          Posted November 11, 2011 at 11:37 am | Permalink

          I’m actually grateful for the uncertainty that I ever existed in the first place. I’m counting on it to give me some comfort when my time eventually comes and I’m forced to face the prospect of death.

          • Al West
            Posted November 11, 2011 at 12:11 pm | Permalink

            Well, for many people, that is a comfort, whether you’re making this remark facetiously or otherwise. Knowing that there is no essential part, no soul, no thing that is unambiguously you without reducing to something else – yes, that seems to give comfort, and has done since Epicurus pointed it out. The best elucidation, and by far the most beautiful, of this thesis is to be found in Lucretius, De Rerum Natura.

      • Tom Dobrzeniecki
        Posted November 12, 2011 at 6:43 am | Permalink

        Occam’s “who is asking the question” makes me think of Descartes.

        I always thought that the highly-praised “I think therefore I am” assumes a lot more than it proves.

        Who is observing the thinking? Who concludes that thinking = existence? To whom is he presenting the proof? By what laws of logic is the proof valid?

        I liked the formulation of Aquinas better, which runs (if I may paraphrase): I am going to assume I’m here. If not, there is nobody here to make an error!

  18. Andrew
    Posted November 11, 2011 at 10:49 am | Permalink

    Stated another way. This is akin to the chance that a blackjack room deals out the specific cards that they dealt last year. But the probability that they a well run room would deal out *some* set of cards over a year is 1.0.

  19. Xenithrys
    Posted November 11, 2011 at 11:26 am | Permalink

    Would another approach to this estimation be to consider the probability of all my alleles being drawn together from the gene pool? It’s a multi-dimensional Punnett square. I’d guess it’s a bit more likely than 1 in 10^2,685,000.
    Factoring in the probability of all my actual ancestors isn’t necessary; I could be me—well, genetic me—with different parents so long as they both carried my alleles among theirs.

  20. Chet
    Posted November 11, 2011 at 12:21 pm | Permalink

    The read probablity that you exist, of course, is 1.

    Uh, no, it’s not. The probability of an outcome isn’t influenced by the fact that it already happened. There’s still (1-p) versions of you that could have existed but don’t.

    The probability of rolling a “6” on a six-sided die is one in six, even if its sitting there showing a 6.

    • Posted November 11, 2011 at 2:36 pm | Permalink

      The probability of anything is based on what you already know of it.

      If you ask what was the probability of a person with your genetic code coming into existence at the moment your dad ejaculated inside your mom, the answer would be 1/280 million or less, since the sperm that became you was one of 280 million in that ejaculate (and there was always the possibility that none of them would have fertilized the egg, or the embryo would not have implanted, thus 1/280 million or less).

      If you ask what was the probability of a person with your genetic code coming into existence at any time before that moment, we have to calculate the probability of that moment occurring (and the moment that led to that moment occurring, and so on), so the chances just get worse and worse the more unknowns you let into the equation.

      There is no single answer to the question “what is the probability of X?” It depends on what you know about the problem. And if you know that X has already happened, then the probability of X are exactly 1, every time.

    • Tom Dobrzeniecki
      Posted November 12, 2011 at 6:32 am | Permalink

      I would disagree. To the extent that it makes sense to speak of the probability of an event that has already happened, the probability of the die being a “6” after it is rolled and has come up as “6” is one. The probability of a another “6” coming up on SUBSEQUENT rolls is 1/6. Those are two different things.

      As Mr. Gerard wrote in comment #1, probability really deals with the state of knowledge of the observer with regard to some future event. I already know the first roll has come up “6”. I DON’T know how future rolls will come up, so the probability is 1/6 for those.

  21. Posted November 11, 2011 at 12:43 pm | Permalink

    Not sure it’s really useful to consider such (im)probabilities.

    Everything is improbable in this way when measured against the infinite possibilities that might have been. What can we actually glean from acknowledging this?

    • Posted November 11, 2011 at 1:22 pm | Permalink

      Ah. And after reading the thread I see that Sastra already made this point.

  22. Posted November 11, 2011 at 1:21 pm | Permalink

    The probability of me existing? i? 😉


  23. Posted November 11, 2011 at 2:25 pm | Permalink

    But if the universe is deterministic, wouldn’t the probability of any person existing become 1?

  24. Posted November 11, 2011 at 3:58 pm | Permalink

    Wow, this makes me feel so special and unique… just like everyone else. 🙂

    As for the lengthy argument above about “do I really exist”: To simplify, I have a statement from my father about owning one axe that has been in the family for over 60 years, and in all that time the axe has had the head replaced twice and the handle replaced three times.

    As nearly every cell in our bodies is replaced every three months (I am not sure about bones and teeth – do carbonate structures count as living cells?) the only continuous thing that we have is our memories, and even then they can be faulty. Besides, I don’t have any evidence that Dr. I. Needtob Athe or anyone else here really exists, as we could all be an elaborate construction of Jerry’s Website. It is highly unlikely, but without us all getting together at some WEIT fan convention, we don’t have actual proof.

    Personally I like to think that you all exist, as a world without WEITers would be less interesting.

    • Filippo
      Posted November 11, 2011 at 5:18 pm | Permalink

      An old timer once told me that when he was a lad he knew of another old(er) timer who had bought his wife an axe for her birthday.

      He couldn’t understand why she was so mad. He said, “It had a pretty red handle!”

  25. Julien Rousseau
    Posted November 11, 2011 at 5:12 pm | Permalink

    James T Kirk voice:

    “Excuse me! What does god need with a fine tuned universe?”

    I find fine tuning (assumed arguando) to be evidence against the existence of god (of the omnipotent variety anyway) as if an omnipotent god exist he would not need to make a fine tuned or even a logical universe but could make one sustained by things falling down because it is down, with the earth flat and supported by pillars, stars and planets moving because angels cause them to move…

    The only kind of universe that needs to appear fine tuned is one that is both improbable and not created by a deity.

    A probable universe doesn’t appear fine tuned and a god created universe doesn’t need to be even grossly tuned.

    Plus, if the universe is fine tuned for anything it is fine tuned to kill us:

  26. Steve Smith
    Posted November 11, 2011 at 5:28 pm | Permalink

    This is meaningless quantification of the sort employed by “sophisticated” and unsophisticated theologians alike. It should be shunned, aside from its utility as an instructive exercise about the pitfalls of such probabilistic calculations.

    What’s the probability that in a single-split experiment, a particle will hit the screen where it’s observed? Zero! Or one chance in ∞. Or, if you prefer, one chance in 10^∞. (And certainly not the a posteriori probability 1.) So what?

    Really specious apologetics from sophisticated Oxonian theologians rest on awful quantifications like this. I was personally introduced via a fomer minister’s-daughter girlfriend to equivalently meaningless calculations on the probability that Jesus is God made by Josh McDowell in his books. Let’s not give any credibility to nonsensical calculations, no matter who makes them.

  27. RFW
    Posted November 12, 2011 at 5:28 am | Permalink

    It seems to me that the question is deeply flawed. At the very least “you” and “exist” are not clearly and objectively defined. And I’m not even sure that “probability” is a valid concept in the present context.

    Jerry, in one of his earlier paragraphs, posits a definition of “you” that includes parentage back to the beginning of time, but from where I sit, a more reasonable definition is that “you” is distinguished by a particular combination of genes. [Note that this leaves out of the question non-genetic aspects of development, but if the definition of “you” includes “did your mother eat a lot of peanut butter during pregnancy?” then the whole issue falls to the ground in a welter of meaninglessness.]

    The question, as I see it, thus becomes (a) how many genes are there in the human genome and (b) how many alleles does each gene have? IOW, how many genetically distinct humans are possible? The probability — if the concept is meaningful in this context — then becomes 1/(number of possible genetically distinct individuals).

    I have no idea how many genes there are in the H. sap. genome, nor how many alleles there are for each one. Even if we just have an average number of alleles per gene, an approximation is possible. Anyone have the numbers handy?

    PS: In this formulation of the question, note that “you” is not necessarily unique. In particular, identical twins are the same “you”.

  28. sailor1031
    Posted November 12, 2011 at 6:57 am | Permalink

    Best not to overthink this. Two possibilities:

    a. you exist – probability of your existence = 1
    b. you do not exist – probability of your existence = 0

    Pick one or the other; you can’t have both.

  29. Kharamatha
    Posted November 12, 2011 at 7:40 am | Permalink

    Is the turtle blind or something?

    Here’s the thing about calculation: Bullshit in; bullshit out.

  30. Kharamatha
    Posted November 12, 2011 at 7:41 am | Permalink

    Given the most factually accurate premisses, the probability of my existence approaches 1.

  31. Torbjorn Larsson, OM
    Posted November 12, 2011 at 1:11 pm | Permalink

    I think Tegmark would have something to say on the size of recurrent versions of “you” in his infinite multiverse.

    But the principle is still the same: it shows the fallacy of the anthropic principle—or of Douglas Adams’s self-reflecting puddle.

    Those are two different things, the a posteriori scientific anthropic principle and the a priori religious anthropic argument. The fallacy belongs to the latter, while the former is untouched by it.

    I would like for scientists to acknowledge what physics have to say about this. The weak anthropic principle is the observation that if parameter varies, the likeliest spot to find observers is where the parameters are compatible with them. That is why, for example, we found life on Earth and not on the Moon.

    The anthropic argument is a large number argument fallacy: large number, therefore gods. It is based on the scam that a priori probabilities has anything to say on a posteriori probabilities. Or in other word that we should find life on both Earth and the Moon.

    In this context, I would think that applying WAP on an individual, let us call it the Coyne Anthropic Principle, would say that it is likeliest to find Coyne’s parents and not other couples as responsible for Coyne’s birth. Which seems like something with a likelihood on the order of ~ 1. =D

    The WAP, in the form of generalized environmental principles (looking for star or dust production) is currently the most predictive theories post-standard cosmology. I refer to Boussou:

    “Using the entropic principle (the assumption that entropy production traces the formation of complex structures such as observers), we derive six predictions that apply to the whole landscape.”

  32. Josh Whalen
    Posted November 26, 2012 at 3:32 am | Permalink

    I find it unlikely it is the “moment in time” that I exist, not “that” I exist. Considering all the possible time before my birth and the considerable amount of time after my death, I find it strange that it’s the moment in the history of the Universe that I exist, opposed to anytime previous or after. What is the probability of that?

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