Hari Seldon, the mathematical genius who invented Psychohistory, has a math question for me:

The Carter Catastrophe argument is that if everyone who ever lived or ever will live were to assume “I’m in neither the first 1% or the last 1% of humans to be born”, 98% of them would ultimately be correct, and the smaller the margin (“I’m not in the first or last 0.1% of humans to be born”), the greater the fraction of humanity for which the statement is true.

An Asimovian galaxy, in which millions of planets are inhabited for tens of thousands of years, would have quintillions of human beings living in it over the aeons, and therefore, we pre-spaceflight humans would be in the first 0.00001% of humans to ever be born.

The argument says that we can safely assume that we are not in that special 0.00001% (or more specifically, that there’s a 99.99999% chance that we’re not), and that therefore, humanity won’t expand out into the galaxy and remain there for tens of thousands of years.

I never liked the argument, or its implication that the grander the sci-fi future, the less likely it is to happen, but have never come up with an actual response to it.

My comment: the argument is not an argument at all, merely a series of three disconnected statements.

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Our own Stephen J remarks: “I have to admit I’m always a little wary of arguments from improbability”

My comment: everyone should be. Most such arguments depend on a faulty idea of probability.

In cases where, like tossing a coin, there are a known and finite number of possible outcomes (heads or tails), and the factors leading to the outcome are known but too chaotic to measure (the initial impulse imparted by the thumb, the Brownian motions of the air), there can be many cases inspected, so that a sense of the likelihood of a given outcome can be assessed: having a coin toss land a hundred times in a row is unusual enough that if you came across one hundred coins all laying heads-up in a line, the conclusion that an intelligent designer placed rather than flipped the coins into position is reasonable.

In a case where we have one data point (for example, human life exists on Earth), and there are an unknown number of outcomes (we could have been fish-men or dinosaur-men rather than hairless ape-men), and the factors leading to those outcomes are unknown AND too chaotic to measure, and there are NO other cases to inspect, no statement about likelihood is sound.

Far, far too often, people merely count the number of current outcomes (how many planets have moons, for example) assume all outcomes are controlled by equal factors occurring in equal numbers, and then made unsound statements about likelihood (that life can arise only on small planets with large moons, like Earth; and since the other nine planets in the solar system have tiny moons compared to their mass, or none, the conclusion blindly leaped-to is that Earth is an unlikely case, hence evidence of ‘fine-tuning.’)

Well, to the contrary, if the laws governing planetary formation were known (we have no first hand observations as yet to study) we might know whether or not rocky, inner worlds with large moons are commonplace.

We might discover, once we make contact with the Sevagram, that the case of Mercury and Venus and Mars with small moons or none is so odd that Galactic sightseers will come from all over the Milky Way to marvel at them, puzzled at these unusual moonless orphan worlds, and astonished to find three in one star system.

Of course, all these sightseers will be mile-long wormlike organisms born in the depth of gas giants larger than Jupiter and hotter than Venus, where all known forms of life are born under conditions extremely favorable to abiogenesis. The high pressures and lead-melting temperatures needed for known biological reactions being entirely absent from Earth, our world will be the only known case of life evolving on a small and deathly cold planet with no noticeable atmosphere. The use of liquid water as a fluid medium in the place of the normal semisolid methane gasses with astonish the scientists from these immense, boiling worlds.

They will have been carefully monitoring the frequencies of gravity waves and neutron vibrations that all the other races use to send messages across the void, wondering why Earthmen have never broadcast any. Their scientists speculate that no intelligent race would use radio waves, due to the massive interference both involved in atmospheric conditions of small planets and large, and due to stellar radio output. And so no one involved in the extraterrestrial search for earthly life bothers monitoring radio frequencies for signs of intelligent patterns.

Part of an ongoing conversation. A reader named the New Number Two has taken time off from his relentless questioning of Number Six, to question the idea of spontaneous generation of life from non life. I reprint his remark in toto, without comment:

Second, remember that you are trying to get those 20 left handed amino acids to form into an extremely complex little machine, and to get that machine started up. The problem is that, to do this by random chance, you must not only have those 20 left handed amino acids form in one place at one time, you must do so over and over, it must be a common occurrence, so that the chances for the formation of that complex little machine are increased. It must, in fact, be so common, that really, you should be able to find it still happening today, since this was supposed to happen on Earth, and this is Earth, so the conditions for it must still exist somewhere at least some of the time.

However…it has never been observed, even under a range of carefully controlled laboratory conditions or in nature, and science has shown that it is so rare for even part of that to happen as to be impossible (assuming that 20 left handed amino acids, not aldehydes, can form in one place, ever). This is the real problem, it must happen over and over and overandoverandover for a very long time, yet it is something that it has been shown cannot even happen once (natural laws prevent it), nor has it ever been observed to happen once. In short, it MUST be so extremely common that we would have seen it or recreated it by now.

Now, let us say that the following happens:
20 left handed amino acids of the proper type for life, by some extremely unlikely fluke, somehow form all at one time and in one place, and somehow are knocked together into the exact relationship to each other that they form the first life, and are started up. On the bright side, this only has to happen once for life to appear. So, three impossible things happen before breakfast, what must we then say? That this must have been planned, and that there is a God.

Note that for God to do it, God only needs it to happen ONCE, in the whole universe. If that were true, we would listen and look and find no other evidence of life anywhere else in this universe, which is exactly what we do find.

Now, you might think that the idea, God, is unlikely. However, the idea, life from non-life by random chance, not planned, has been shown to be impossible, so whatever remains, however improbable, must be the truth.

Note also that the idea, “God is improbable” is nonsense, one cannot calculate the chances of an extra dimensional being of infinite power and intelligence, we have never even observed this extra dimension, and thus have no idea what is possible there. The only reason people say God is improbable is because God is improbable for the natural laws of this universe, but that assumes that this is the only place there is, by blind faith. The other option is that there is a God, for which there is at least some evidence, people who said that they observed Him, “that which we have seen and heard” and “touched and handled”. So there are two choices, “there is no god”, the evidence for which is zero, and “there is a God”, the evidence for which is greater than zero, including the evidence that, despite it having been proved impossible by random chance, there is life on Earth.

However, we are still searching for intelligent life on Earth.