  Since we only care about the conditional if oj is a cloud, so is ok, it is clearly acceptable to assume that oj is a cloud for the sake of the argument. And S3 is guaranteed to be true by the set up of the problem. The main issue then is whether S2 is true. As Hudson notes, there appear to be some clear counterexamples to it. The fusion of a cloud with one of the water droplets in my bathtub is clearly not a cloud, but by most standards it differs minutely from a cloud, since there is only one droplet of water difference between them.