Tim Maudlin here is talking about the Gibbsian approach to explain the second law of thermodynamics. He introduces the “coarse-graining” procedure, but then adds “but what the hell is going on here? how do you think about these interventions?

Here is the answer: the observer makes an inference based on what they can see about the system. That’s it. The second law is about the inferential process of the observer, not about the underlying physics. We have written about this in a few papers, and I have given several talks on this idea. It all makes perfect sense to me!