|Orange and Yellow, Mark Rothko|
Like the Anthropic Principle, the deeper you look into it the more you understand.
Why can we say this?
Because the process of producing a new individual ensures that the genes get shuffled and there are far more possible combinations of genes than there are humans alive now or have ever been alive, so the chances of producing exactly you, of all the trillions of possible humans, is almost vanishingly small.
And yet, given the nature of human reproduction, once the conditions for one of several million sperm finding and fertilizing an ovum had been created, the likelihood of producing a human being was highly likely. The only thing that was unpredictable was exactly what hand of genes that individual would be dealt by the process.
Ask your parents if they knew in advance what you were going to be like before you were conceived? If they are honest they will tell you they didn't even know what sex you would be, let alone how tall you would grow, whether you would be athletic or academic; what your shoe size at age 6 would be. Slightly more predictable would have been your skin, hair and eye colour. About the only thing they knew for sure was that they were going to have a child and that that child would have a mixture of both their sets of genes.
To illustrate this for yourself, take two packs of cards and shuffle each pack. Now deal twenty-six cards from one pack and twenty-six cards from the other into a single 'pack' of fifty-two cards.
Now examine those cards.
Now calculate the probability of dealing just those fifty-two cards to produce exactly that 'pack'. For the mathematicians here I think it's 1/((52!-25!)^2), but correct me if I'm wrong. In any case, it's a really small number.
No, don't bother. It's hugely unlikely. Try it again and see if you get the same result. Keep trying all day if you wish, the probability of you repeating the initial 'pack' is almost vanishingly small. In fact, if you could arrange to deal a similar hand every two minutes you probably wouldn't deal the same hand twice before the sun explodes.
But was there anything special about that first deal which produced exactly that result? Was it any different to the subsequent ones which produced different results?
There is nothing different at all, which is why you can be certain that, if you have any siblings, they will not be exactly like you, unless you are an identical twin, in which case you will both have inherited exactly the same set of genes because you both developed from a single fertilized ovum.
And now comes the magic bit.
We are discussing the probability of you being alive now. To do that we don't need to calculate the probability of you having the set of genes you have in your cells, because THAT doesn't tell us the probability of you being alive. It tells us the probability of you having the set of genes you have but that's not the same thing at all. If someone had forecast in advance exactly what combination of genes you would have, and they had been right, there would certainly be some explaining to do. In fact, the chances are so small that it would be vastly more likely that there was some trickery involved.
No. What we are discussing is the chance of you existing here and now in this universe and to do that the calculation is simple and the result is perhaps surprising.
There are only two possibilities we need consider: either you exist here and now, or you don't. So, the probability of you existing here and now is either 1 (certain) or 0 (impossible).
To be discussing the probability of you existing here and now we must both be in a universe in which you exist here and now. So the fact that were are discussing it means we MUST be in a universe in which you exist and we must be discussing it now.
So, the probability of you existing is not the vanishingly small figure it seems to be; it is certainty. We could not be holding this conversation otherwise. The fact that were are holding the conversation guarantees that you exist. If it were impossible we could not be discussing it.
It is exactly the same as calculating the odds on a horse winning the Grand National or Kentucky Derby AFTER the race has finished. It is certainty for the winner and zero for all the others. Before you were born the odds on exactly YOU being born were tiny. AFTER you were born it became certain.
This is the Anthropic Principle, and it holds true for other questions.
For example, when discussing why the universe seems to be right for intelligent life to evolve in, we can ONLY be discussing that in a universe in which intelligent life developed, hence the probability is NOT the vanishingly small figure creationists and religious apologists claim; it is certainty.
Why did evolution lead to humans? Leaving aside the fact that evolution also lead to every other form of life, extinct or living, humans can ONLY be discussing that on a planet on which humans evolved. Again, the probability is not some infinitesimally small and impossibly unlikely accumulation of improbabilities that religious apologists try to tell you it would need to be for evolution to be true; it is certainty.
But, you are still special. You share in the great good fortune of this universe existing at all; of this planet forming at all; of replicators developing at all, and of humans evolving at all. You could have lived before humans had evolved an intelligent brain so you may not have been capable of appreciating the magnificence of this planet and of the cosmos.
What makes you special is not the hand you have been dealt but the great good fortune you had in being metaphorically dealt at all. Had your parents has sex at a different time or place, and had their parents done likewise, neither they nor you would have been born. But in all probability, someone would have been and they would have been dealt the winning hand in the game in which every hand is a winner.
For very many people over much of this planet, life is better than it has ever been. Most people are better housed, better clothed, better fed, have more choices in life, can travel further and faster, have better health and are better educated than their parents and grandparents. Now is probably the best time for humans to have lived in the history of humanity.
It will not always be so, and you may never have been born at all.
But we should never forget, that is not true for many people, especially in Africa and parts of Asia. For some people, life is still as nasty, brutish and short as it was once for us all. For many people the question is not why am I here, but will I have anything to eat or drink tomorrow and will my children still be alive.
Make the most of this one hand that chance had dealt you.