I have redefined them! Those limits, that is. This is the view of Father Robert Barron, in response to -- well, something I said, but it's hard to pinpoint exactly what. But I know it was me and not some other Sean Carroll, because there's a video in which my picture appears a couple of times. I think his remarks were spurred by Natalie Wolchover's article about my piece on why the universe doesn't need God. (Here is a related article, not quite a transcript of the above video but close, in which he mentions Natalie's piece but not mine.) He may have read the original piece, although it's unclear because he doesn't link to anything specific, nor does he reference particular arguments from the essay itself. He also refers to a book I've written, but none of my books actually fit the bill. And he talks a lot about my arrogance and hubris. (I've finally figured out the definition of "arrogance," from repeated exposure: "you are arrogant because you think that your methods are appropriate, when it fact it's my methods that are appropriate.") In any event, the substance of Fr. Barron's counter-argument is some version of the argument from contingency. You assert that certain kinds of things require causes, and that the universe is among those things, and that the kind of cause the universe requires is special (not itself requiring a cause), and that special cause is God. It fails at the first step, because causes and effects aren't really fundamental. It's the laws of nature that are fundamental, according to the best understanding we currently have, and those laws don't take the form of causes leading to effects; they take the form of differential equations, or more generally to patterns relating parts of the universe. So the question really is, "Can we imagine laws/patterns which describe a universe without God?" And the answer is "sure," and we get on with our lives. As good scientists, of course, we are open to the possibility that a better understanding in the future might lead to a different notion of what is really fundamental. (It is indeed a peculiar form of arrogance we exhibit.) What we're not open to is the possibility that you can sit in your study and arrive at deep truths about the nature of reality just by thinking hard about it. We have to write down all the possible ways we can think the world might be, and distinguish between them by actually going outside and looking at it. This is admittedly hard work, and it also frequently leads us to places we weren't expecting to go and perhaps even don't much care for. But we're a flexible species, and generally we adapt to the new realities. Which reminds me that I still owe you a couple of reports from the naturalism workshop. Coming soon!