I previously mentioned this debate a month ago and predicted that Sean Carroll is unlikely to do very well. The debate happened last Friday and Sean posted his post-debate reflections on his popular blog (the full video will be posted soon). Some excerpts:

I think it went well, although I can easily think of several ways I could have done better. On the substance, my major points were that the demand for “causes” and “explanations” is completely inappropriate for modern fundamental physics/cosmology, and that theism is not taken seriously in professional cosmological circles because it is hopelessly ill-defined (no matter what happens in the universe, you can argue that God would have wanted it that way). He defended two of his favorite arguments, the “cosmological argument” and the fine-tuning argument; no real surprises there. In terms of style, from my perspective things got a bit frustrating, because the following pattern repeated multiple times: Craig would make an argument, I would reply, and Craig would just repeat the original argument.

The cosmological argument has two premises: (1) If the universe had a beginning, it has a transcendent cause; and (2) The universe had a beginning. [...] My attitude toward the above two premises is that (2) is completely uncertain, while the “obvious” one (1) is flat-out false. Or not even false, as I put it, because the notion of a “cause” isn’t part of an appropriate vocabulary to use for discussing fundamental physics. [Emphasis mine]

The Aristotelian analysis of causes is outdated when it comes to modern fundamental physics; what matters is whether you can find a formal mathematical model that accounts for the data. 

Sean goes over a couple of mistakes he thinks he made in the debate, basically being blindsided by WLC bringing up obscure papers and misinterpreting them to suit his argument. 

Sean's reflections are very detailed and worth reading, though I found them hard to summarize. It looks like WLC did his homework better than SC, but it's hard to tell whether it mattered until the video is made public and various interested parties gave their feedback. Another couple of quotes, with my emphasis:

For my closing statement, I couldn’t think of many responses to Craig’s closing statement that wouldn’t have simply be me reiterating points from my first two speeches. So I took the opportunity to pull back a little and look at the bigger picture. Namely: we’re talking about “God and Cosmology,” but nobody really becomes a believer in God because it provides the best cosmology. They become theists for other reasons, and the cosmology comes later. That’s because religion is enormously more than theism. Most people become religious for other (non-epistemic) reasons: it provides meaning and purpose, or a sense of community, or a way to be in contact with something transcendent, or simply because it’s an important part of their culture. The problem is that theism, while not identical to religion, forms its basis, at least in most Western religions. So — maybe, I suggested, tentatively — that could change. I give theists a hard time for not accepting the implications of modern science, but I am also happy to give naturalists a hard time when they don’t appreciate the enormous task we face in answering all of the questions that we used to think were answered by God. [...]

To me, Craig’s best moment of the weekend came at the very end, as part of the summary panel discussion. Earlier in the day, Tim Maudlin (who gave an great pro-naturalism talk, explaining that God’s existence wouldn’t have any moral consequences even if it were true) had grumped a little bit about the format. His point was that formal point-counterpoint debates aren’t really the way philosophy is done, which would be closer to a Socratic discussion where issues can be clarified and extended more efficiently. And I agree with that, as far as it goes. But Craig had a robust response, which I also agree with: yes, a debate like this isn’t how philosophy is done, but there are things worth doing other than philosophy, or even teaching philosophy. He said, candidly, that the advantage of the debate format is that it brings out audiences, who find a bit of give-and-take more exciting than a lecture or series of lectures. It’s hard to teach subtle and tricky concepts in such a format, but that’s always a hard thing to do; the point is that if you get the audience there in the first place, a good debater can at least plant a few new ideas in their heads, and hopefully inspire them to take the initiative and learn more on their own.

Sean concurs: "If we think we have good ideas, we should do everything we can to bring them to as many people as possible."

I hope Luke or someone else will find time to watch the video once posted and give their impressions.

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For context, here are three of my posts from years ago about William Lane Craig's debates with atheists. I haven't looked at them for a long time so I don't know if I agree with everything in them, but I probably still agree with their general tone:

I watched part of this, and I came away with a very favorable impression of Carroll's performance. That said, I have no real idea how to score these things as wins or losses, especially when I have such a heavy prior bias. I will say, though, that Jeffery Jay Lowder, an atheist who follows these debates closely and is usually very critical of Craig's oppponents, said that Carroll dominated the debate and did as well as anybody who has ever debated Craig.

Or not even false, as I put it, because the notion of a “cause” isn’t part of an appropriate vocabulary to use for discussing fundamental physics.

Really? I don't know fundamental physics (I take this to mean quantum mechanics and general relativity) well enough to directly say anything about it. However, as far as I know, all of the mesoscopic stuff (electromagnetism, elasticity, thermodynamics, chemical processes, etc. on the scale of everyday objects) obeys causal differential equations, by which I mean the subject matter of this book. The same is true, to the extent that I know anything of the matter, of quantum mechanical descriptions of the time evolution of a system. Some of these also have non-causal formulations (e.g. principles of least action), but there is always a causal description: one that does not require any future boundary conditions in order to calculate future trajectories.

If physicists don't explicitly talk about causes, it's because the concept is too basic and agreed-on to need talking about. They don't talk much about "truth" either. Or "arithmetic".

Classical physics, excluding thermodynamics, is invariant under time reversal. I certainly wouldn't call that causal, but maybe I'm missing something.

Also quantum physics, in no-collapse interpretations. (Except for a few processes like kaon decays, that arguably are time invariant "in spirit" because they are CPT invariant).

A couple of points:

Some of these also have non-causal formulations (e.g. principles of least action), but there is always a causal description

Sort of true, although to make a "causal description" of GR one has to do unspeakable violence to the Einstein equation, which simply states that curvature = energy-momentum density. It also excludes many of the popular solutions with closed timelike curves and other anomalies. In any case, if you don't need a causal formulation, or if you can derive it from a non-causal one, then asserting that causality is essential in physics would be reaching.

If physicists don't explicitly talk about causes, it's because the concept is too basic and agreed-on to need talking about.

That's not true. Physicists do explicitly talk about causality, as in, how much of the future can be influenced by the past. Scott Aaronson recently wrote a paper about it.

All that said, however, I believe that what SC and especially WLC meant by causes in their debate was "external causes", more in a sense of a creator, or at least fire in the equations, not the mundane idea of equations of physics being castable in a hyperbolic form. And that vague notion of external causes is what SC objected too.

You are quoting out of context. The issue is the cause of the big bang and the cause of the particular values of fundamental constants. That physical laws say that the past causes the future is relevant to neither of these points.

(Shminux said the same thing, but buried it by pursuing your tangent.)

I find myself put off by Craig's use of disagreements and thought experiments in academic disciplines (which are the sign of a healthy field!) as a weapon against them. For example he uses speciesism to attack against non-theistic moral philosophy, instead of using it as a means of talking about what properties are relevant for moral consideration - which was its original purpose. And he uses Hilbert's Hotel to assert that infinities are "paradoxical" - even though they are perfectly logically consistent, and much of modern mathematics is based off of them.

I understand that he is trying to win, he doesn't care about honesty, but that doesn't make it any less off-putting.

I wonder if he would agree with

[-][anonymous]10y00

Debates can be somewhat useful for finding out the truth when the debaters are matched in debating skills. But when one of the parties is more skilled than the other, this advantage usually determines which side people perceive to have won (excluding those already strongly committed to either position). William Lane Craig's debating skills are remarkable, and superior to those of nearly everyone he has engaged in debates with. (For an exception, check his debate with Arif Ahmed.)

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