Paper by Anders Sandberg, Eric Drexler and Toby Ord of the Future of Humanity Institute, Oxford University made the news last week. “Dissolving the Fermi Paradox“, on Arxiv (and therefore not yet watered down by peer review).
The point I want to make about it is simple enough, and appears in contrast to the opening sentence of the abstract: “The Fermi paradox is the conflict between an expectation of a high ex ante probability of intelligent life elsewhere in the universe and the apparently lifeless universe we in fact observe.”
There is no such probability, ex ante or ex uncle. The History Channel aside, and not counting non-material beings, we do observe an apparently lifeless universe. That is interesting. The question is why.
Now no proposition has a probability. All probability is conditional on the evidence assumed. Different assumptions give rise to different probabilities. We have high or low probabilities on whether other (non angelic) rational beings besides ourselves exist depending on what assumptions we make about such creatures.
Ultimate knowledge consists in the cause of why other (material) rational beings exist, or why they do not. To my knowledge such knowledge does not exist. Though there are arguments.
One, we have no idea how any life arose in the first place. It could have been miraculous, or it could have been the result of certain forces acting on inanimate matter (the miraculous encompasses the second explanation). Either proposition is a supposition, themselves the end results of arguments in their favor. God caused life to begin, “through Him all things were made”, or life arose by a certain physio-chemical operation. Both are believed on faith.
Once life appeared, it changed. There had to be an ultimate architect—creator of at least the nature of physical existence—that accounts for the mechanisms of change. The assumption is that given life arose at places far distant from us, places comprised of the same physical stuff as us, it possess the same nature and therefore the same mechanisms of change. It does not follow from these assumptions that the mechanisms of change must necessarily have led to creatures possessing the ability to be rational.
Since the mechanisms are not known with specificity, since they are only crudely guessed at, to believe creatures possessing the ability to be rational arose anywhere else is a decision, a guess, one made without proof. Proof would be cause, and the cause comes in specifying the exact precise mechanisms both for life’s initiations and for its changes. These are lacking.
A probability may be formed, almost surely unquantifiable, from making further suppositions about both exact precise mechanisms, that creatures possessing the ability to be rational did arise. These mechanism-suppositions have to be augmented by guesses or observations about other places that possess the same physical stuff like us. There is less controversy in those, and some are made in the linked paper.
Once creatures possessing the ability to be rational came about at some distant place, however they came about, they had to move from non-rational to rational. Since rational creatures are different in essence or nature from non-rational creatures, there has to be a third mechanism causing the move. God is responsible is one explanation, well in accord with observation of ourselves and angelic beings. There is no other explanation except that some mysterious yet-heretofore unknown mechanism did it. Again, both propositions are matters of long arguments, but the “just happened” is weak at best, since rationality arising, i.e. “just happening”, from non-rationality would appear impossible, since intellects are not material, and are therefore not able to be operated on by physical mechanisms.
Well, here we are. Gather all arguments on both sides together. We have God created life and the mechanisms, the mechanisms led to creatures possessing the ability to be rational, and God imbued some of these creatures with rationality. Or some unknown cause made the mechanisms, some unknown mechanism made life, further not-fully known mechanisms caused changes, and a still-yet-unknown mechanism caused rationality. Call these hypotheses God and Unknown.
Whichever you pick, it is not at all clear whether material creatures which are rational exist elsewhere. There isn’t anything forbidding such creatures in the God hypothesis, nor in the Unknown. So we can’t work with cause. We have to supply other assumptions from which we can form a probability. Problem is, there are no such unique assumptions. Therefore, there will no unique probability.
Of course, you can make the assumptions sound learned by attaching math to them, as the authors have done, following a tradition initiated by Drake. The math makes the assumptions sound more valid than metaphysical propositions, at least to some. And until you realize any number of equations can be substituted for the ones the authors picked.
Fermi’s paradox is a metaphysical matter, because under either hypothesis, God or Unknown, it is a valid question to ask, “If other rational creatures exist, where are they?” Searching for the answer is therefore not nuts. Under the absence of any direct observation of these creatures, the answer must remain philosophical.