 What the reader is supposed to do is to imagine a series of such interactions, between the system and the thermometer, between the thermometer and the light, between the light and the retina, etc., and rely on the absence of interference at each step to argue that, even if we describe a number of systems using intervention \(\mathbf{2}\), they behave for the purpose of the application of intervention \(\mathbf{1}\) as if they had collapsed already. In this sense, even though he is quite clearly not thinking in terms of mechanisms for suppressing interference, he is relying on decoherence. A fuller treatment (e.g. a detailed model of how the thermometer interacts with light, and some of the light is then sampled by the eye) would resemble more closely an analysis in terms of environmental decoherence. 