The Fine Tuning Argument Debunked

skydivephil sent us this video of Monica debunking the fine-tuning argument. I met them at TAM London and realized immediately that they were awesome, but I didn’t realize how awesome. This is a cogent, easy-to-understand explanation of why William Lane Craig et al are wrong to suggest that there must be a god because Earth is just so super.

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor. Twitter @rebeccawatson Mastodon Instagram @actuallyrebeccawatson TikTok @actuallyrebeccawatson YouTube @rebeccawatson BlueSky

Related Articles


  1. This is a great video, with sound reasoning. The problem is that believers will wash all that reasoning away with one sentence: God is too complex for us to begin to understand, so we can’t see or understand the evidence that exists to prove it. So for people who already use and rely on reason, this is a great example of clear thinking. I fear, however, it will win no arguments with believers.

  2. I didn’t get to see the whole video yet, but the first few minutes seemed pretty specious. It sounded like she was saying: “The universe clearly isn’t fine-tuned for life because there is no life in the universe.” Then, when she talked about the age of the universe, she divided by a googol, implying that it doesn’t count as life unless it has been around for a significant portion of the age of the universe. Neither of those seem to be very strong arguments against anything (it reminds me of the old clichéd argument: “in a thousand years, no one will care that you did x, so do/don’t do x”). Am I missing something?

  3. @Demosthenes: She is demolishing the argument that the universe is fine-tuned for life by showing that most of it (either volumetrically or temporally) is utterly hostile to life.

  4. Buzz PArsec has it exactly right. Imagine an underwater cave 1*10^86 cubic meters in volume. Now imagine only 1 cubic meter of that cave had a pocket that could support human life. Should we assume the cave was finely tuned for life?
    The universe is the same.

  5. @scribe99: I came to THAT conclusion when people like Tiny Tim were able to make successful recording careers out of sounding like Tweety Bird being tortured

  6. @Buzz Parsec: Yes. I misunderstood the point of dividing by time and space (I thought she was talking about ‘inhabited’ planets rather than ‘habitable’ ones). Nevertheless, the only time I’ve heard the Fine Tuning Argument it’s been with reference to the Earth, and specifically to the portion of it where life exists. I’ve never heard anyone claim that the entire universe is fine-tuned for life, and I doubt that anyone would make that claim, so I don’t see the point of averaging habitability by the entire volume of the universe.

  7. Watch any debate between a theist and a non believer and you will hear this argument used over and over although William Lane Craig is most well known for using it. Yes it is applied to the whole universe because it is reffering to the values of physical constants.

  8. I think the “Goldilocks Zone” is so important to life because life itself is an expression of the complexity at the boundary between chaotic and orderly systems. At a certain point the balance between the two is just right to give rise to an amazing complexity that is not exactly stable and not exactly unstable.

    If this is the case, then any values for the constants of nature that allowed for the coexistence of both chaotic and orderly systems would very likely eventually result in life of some sort at the boundary between them. I find it hard to imagine that there are very many combinations of constants that would result in pure chaos or pure order, so I suspect that life is actually quite probable, almost regardless of the values of the constants.

  9. Hi guys – excellent video. Sorry I just got to this, but I thought it merited setting up an account so I could post. :) If I think about debating a highly sophisticated theist, this is the one argument that I dread most, though in fact it’s nothing but the same fallacy that Paley made with his watchmaker story – the constants of the Universe appear fine-tuned, but we don’t understand all the laws that constrain them, so we’re really not qualified to make the leap of logic that they *are* tuned.

    When I first heard this, my first thought was back to a talk given by John Webb & collaborators when I was a PhD student when they were just releasing the first details on the possibility that the fine structure constant might vary. If constants can vary then I guess they’re not that finely tuned after all? Also there’s a common trick debaters use when they say that gravity is fine tuned to something like one part in 10^38. That sounds amazing, but what they mean is that the strong nuclear force is that much stronger than gravity, and theoretically there’s no reason why gravity shouldn’t be 10^38 times stronger. I don’t see why they choose that arbitrary limit, but meh… Anyway, that’s sneaky, and worth mentioning.

    My one quibble was with your statement about the suggestion that the creator had to create life and therefore the Universe wasn’t so finely-tuned for life after all. Well, I guess one could use the analogy with roads – there are loads of roads all over the world that are beautifully constructed for cars to travel on them efficiently from A to B, but we shouldn’t therefore expect cars to start appearing on them, we expect cars to have a designer & engineers to construct them first.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Back to top button