Scott Adams, the cartoonist behind Dilbert, posted a thing yesterday.
He was considering a step-by-step argument, which seems to result in the likely conclusion that life on Earth was the result of a deliberate seeding operation by aliens. Read it through on his blog before deciding it’s nonsense. I’ve summarised it very coarsely, and it’s more lucidly reasoned out than you might think.
His point, though, was to ask his readers to spot the flaw in the logic, which he finds himself unable to do, despite assuming apparently a priori that there definitely is a flaw. He doesn’t lay out explicitly why he’s unconvinced by what seems to him like watertight reasoning, and you may in fact be in agreement with the conclusion yourself.
But, a few problems with it did occur to me as I was reading, so I thought I’d try fleshing them out here, in a purely speculative and thoroughly uninformed manner.
– Firstly, I think the principle of indifference may be being inappropriately applied.
This is a mathsy thing. The idea is, you can basically guess equally between a number of possibilities when you don’t know anything about what’s going on, and simply have a number of options presented to you. If I ask you to guess what playing card I just randomly picked out of a deck, for instance, you might just as well say the nine of diamonds as the seven of spades. Nothing stands out about any one option, so you can apply the principle of indifference, and treat them all as being equally likely.
But sometimes it’s inappropriately applied. One way I’ve seen this done before is to argue that our Universe is likely to be only a simulation. We think we live in a reality that really exists, but as we approach a time when it’s feasible to create a Matrix-like simulation in which conscious beings could live unawares, we have to consider that maybe we already exist in such a simulation.
But maybe the reality that’s simulating us is itself only a simulation, within a reality which is also only a simulation, and so on, Inception-style, with as many layers as you like. Then, the possibility that ours is the real reality, and we just haven’t created any universe simulations ourselves yet, is just one among indefinitely many. So (the fallacious argument goes) the odds on that being the case are vanishingly small.
The reason it’s not convincing is that all the various options – that our reality is real, or that we’re the first simulation, or the second, or the seventy-fourth – should not be treated as equally likely. The idea that our reality is real makes fewer assumptions about the plausibility or the existence of colossal universe-simulating machines, and can legitimately be given a greater weight than the other options.
Scott’s argument may suffer from the same false application of this principle. It says: we could soon be the first species ever to send spaceships to other planets and “seed” them with the building blocks of Earth-like life – or we could be one of many stops in an indefinitely long chain of other species which have already done that. That is, Earth may have been seeded by an alien civilisation, which itself was seeded by another, and another, and so on.
If you consider that we could be at any point in the chain, and treat them all with the principle of indifference, then it may seem unlikely that we just happen to be the first, “unseeded” life-forms in the cosmos. But there are different assumptions involved in “It’s already happened” than “It hasn’t happened yet”, and so, barring any other evidence which directly supports it, I don’t think we’re obliged to give the possibility that our own world was “seeded” so much weight.
– Because, don’t forget, there is no other evidence directly supporting the idea that this seeding is what’s happened here. However solid the arguments might be that it could happen, or that it’s virtually inevitable to happen with any life that reaches a certain threshold of intelligence, it’s all just speculation. Nothing wrong with that, but it’s not the same thing as empirical data. However unlikely you want to argue that the “unseeded Earth” possibility is, it’s entirely consistent with the current data, and it makes fewer assumptions about the Universe than the alternatives.
– I’m also not fully convinced that any intelligent life-forms would necessarily reach the point where this seeding of other worlds becomes both practical and desirable. There are various assumptions on which this rests, like our (or other life-forms’) ability to get that far technologically without destroying ourselves; the superior plausibility of the seeding option over any other methods for sustaining life; the eventual success of even a well planned seeding mission in giving rise to intelligent life again; and the timescale necessary for this to happen. (We have pretty good evidence that life on Earth has been evolving slowly for about a quarter of the age of the Universe. It can’t have happened that many times, going by this iteration rate.)
– We also have no idea how likely the possibility of alien life actually is. There’s so much uncertainty over so many variables of the Drake equation, that whether or not any other life has yet been able to arise anywhere else in the galaxy is still deeply contentious. A lot of things needed to be exactly right on Earth for life to get going and start becoming complex and interesting, and we don’t really know how rare those conditions are. The scenario of other aliens having got there before us is far from being a given.
Leave a comment if there are any more obvious points leaping out at you which demonstrate that one of us is going wrong.