 But only prima facie. A number of criticisms have been leveled against this maneuver. One that seems on the mark is the observation that if classical mechanics is to be a universal theory, then the environment must be governed by the laws of classical mechanics as well. The environment is not some mechanism outside the governance of physical law, after all, and when we treat it too, the “deus ex machina”—the random perturber—disappears. If we treat the gas-plus-the-container walls as a classical system, it is still governed by time-reversible laws that will cause the same problem as we met with the gas alone. At this point one sometimes sees the response that this combined system of gas plus walls has a neglected environment too, and so on, and so on, until we get to the entire universe. It is then questioned whether we have a right to expect laws to apply universally (Reichenbach 1956: 81ff). Or the point is made that we cannot write down the Hamiltonian for all the interactions a real system suffers, and so there will always be something “outside” what is governed by the time-reversible Hamiltonian. Both of these points rely, one suspects, on an underlying instrumentalism about the laws of nature. Our problem only arises if we assume or pretend that the world literally is the way the theory says; dropping this assumption naturally “solves” the problem. Rather than further address these responses, let us turn to the claim that this maneuver need not modify the laws of classical mechanics.