  This is a quite ingenious approach, and it deserves some attention in the future literature. It is hard to say what will emerge as the main costs and benefits of the view in advance of that literature, but the following two points seem worthy of attention. First, if we are allowed to appeal to the principle that no cloud is a proper part of another, why not appeal to the principle that no two clouds massively overlap, and get from 4 proto-clouds to one actual cloud that way? Secondly, why don't we have an object that is just like the old a + w1, that is, an object that has w1 as a part at r1, and does not have w2 (or anything else) as a part at r2? If we get it back, as well as a + w2, then all of Hudson's tinkering with mereology will just have converted a problem of 4 clouds into a problem of 5 clouds.