I was just watching this video clip of Luke Barnes talking to Robert Lawrence Kuhn about extraterrestrial life. Kuhn brought up an interesting point. He said that if it turned out that the universe was teaming with life, an argument could be made either by a theist or an atheist, and both would make sense. The theist could say, "See? With all this life, clearly the universe was fine-tuned to have life." An atheist could say, "See? With all this life, human life is not special; therefore, the universe was not created for us." These aren't exactly opposite claims, but I still found it interesting.
But anyway, it inspired this post. I just want to talk about the theist response. This response is an answer to an objection to fine-tuning I hear a lot. This is not one of my original objections, but since it comes up so much I figured it was worth responding to. The objection is that if the universe were fine-tuned for life, then we should expect there to be more life. But most of the universe is hostile to life, so the universe isn't fine-tuned for life.
I have a lot of things to say about that. First of all, the universe could be fine-tuned for life even if there was no life in the universe. To be fine-tuned for life only means the universe has the necessary laws and constants so that life is possible in the universe. The universe could, given its laws and constants, support life under some set of circumstances constrained by those laws and constants. In other words, with those laws and constants, it's possible to create a scenario in which life could exist. Without those laws and constants being what they are, life wouldn't even be possible.
Second, if you draw the conclusion that a Divine Engineer fined-tuned the universe so that life is possible, that tells you nothing about how much life that engineer wanted the universe to support. So you can't make any predictions about how much life the universe should contain just from supposing that the Divine Engineer wanted the universe to have some life.
Third, the existence of any life at all, be it ever so rare, shows that the universe is capable of supporting life, and if those laws and constants have to be tuned to precise values in order for that life to exist, then the universe is fine-tuned for life. If life is extremely rare, that does nothing at all to undermine the claim that the universe is fine-tuned for life because if it wasn't fine-tuned for life, then no life could exist anywhere at all in the universe. So you only need one example of life to support the claim that the universe is fine-tuned for life.
Fourth, if the Divine Engineer made the universe in such a way as to make life possible, that doesn't mean life was the sole purpose for creating the universe. As an analogy, suppose you want to design a smart phone capable of taking pictures. Well, you'd need to make the phone in such a way that it could support the existence of a working camera. The fact that you had that purpose in mind when designing the phone doesn't mean that the whole phone is nothing but camera lenses or camera hardware. In the same way, the divine Engineer may have had all kinds of purposes for creating the universe besides just life. But it would still have to be fine-tuned for life in order to support life.
Fifth, it could be, for all we know, that even if you had the most ideal life-friendly laws and constants, the actual emergence of life is still an improbable event. If that were the case, then we should expect life in the universe to be rare even if it is fine-tuned for life. But as long as it still emerges, then the purpose of fine-tuning the laws and constants will have been served. Until we figure out what the chemical pathway was from simple elements and compounds to the first functioning cell, it will be very hard for us to say how probable or improbable the emergence of life is given those basic elements and compounds.
Sixth, the fact that most of the universe is hostile to life is kind of necessary for there to be life at all. I got this point from Luke Barnes. Imagine if instead of most of the universe being empty space, it was filled with life-friendly atmosophere. Well, that would be a disaster because then you couldn't have stable planetary orbits because the atmospere would create too much drag, and all the planets would burn up in the atmosphere or fall into their stars and burn up. Also, gravity would cause all the atmosophere to clump up and probalby form stars or something, and you'd end up with empty space anyway. There'd be so much mass in the universe that you'd have to counter it by a whole lot more dark energy just to keep the universe from collapsing. That's just one example of how trying to make the universe more life-friendly would accomplish the opposite. Luke said that you really need a lot of empty space in order to make the universe habitable.
That's about it. If I think of anything else, I'll edit this post.
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