Last year, I began an internet discussion with a non-theist named Aron from Maryland. At the moment, this discussion is ongoing, and will be continuously updated here, so check back often.
We started out talking about the Transcendental Argument for God's existence (TAG), and in the end agreed how it could be used in a bigger cumulative case.
We have since transitioned to discussing the fine-tuning argument (FTA). It's great discussion, and I hope others will follow along.
Transcript of our discussion about TAG (we start transitioning to discussing FTA at the end):
FTA part 1: Aron challenges that the probability if fine tuning is lowA beginning to our discussion of the FTA, where Aron opens with acknowledging our general agreement of how to apply the TAG, and also suggests the probability that our universe would be the way it is (usually called "finely-tuned" in theistic circles) in not actually low:
FTA part 2: General questions for AronI answer with some general questions for Aron to make sure we're not talking past each other:
FTA part 3: Aron answers my general questionsAron then answers my general questions, so I think we're ready to start the discussion in earnest.
FTA part 4: Why fine-tuning means the universe is improbableI begin to lay out the fine-tuning argument and press why we can say the probability that the fine-tuning would occur without God is small. Please note that Aron and I both agree that the constants of the universe are finely-tuned, in that they cannot vary by much before the universe is no longer life permitting.
FTA part 5: Aron introduces the normalizability problemAron responds by noting that since we are appealing to "possible universes" (which may not even exist), we have no idea what values of the constants of physics are more probable than others, so we must assume any value has equal probability to any other. However, since we have no way to restrict the ranges these values may take on, we have to allow for infinite ranges (i.e., zero to infinity). Therefore, the probability distribution is not really a probability distribution. In this statement, Aron is introducing the "non-normalizability" problem. To strengthen his argument, Aron cites famed Christian apologist Dr. Timothy McGrew. This is a big deal.
FTA part 6: Defying intuition, the multiverse, or necessityI agree that the non-normalizability problem that Aron introduced in the previous post is a big deal. Then I lay out how the intuition of the FTA argument is layered, and every time a skeptic denies the intuitive conclusion that fine-tuning leads to the conclusion that God most likely designed the universe, he or she must give up some more obvious conclusion for a more skeptical one. This is my "How deep does the rabbit hole go?" story. But, we do need to go deeper, so I note that there are two options. Either the multiverse exists, in which case the probabilities are indeed normalizable (because there is a real mechanism generating universes), or our universe is all there is. In the second case (which Aron wants to go with), even if the probabilities are meaningless (since there is only one universe), we still have a situation (fine-tuning) that demands an explanation.
FTA part 7: Aron asks clarifying questions
Aron reasserts that the non-normalizability problem, since it leads to the conclusion that probabilities are meaningless, also means that the fine-tuning argument just does not work. He asks for more clarification and explanation on my part.
FTA part 8: Clarification on the multiverse vs. necessity
Here I clarify what I said in my previous post. In particular, I clarify that if Aron wants to go with a single universe, and claim that fine-tuning does not lead to small probabilities, this is the same as saying (1) the universe just IS, with no explanation for it, and none needed; and (2) the universe just IS FINELY-TUNED FOR LIFE, with no explanation for that either, and none needed.