  It seems reasonable to expect something like philosophical reductions to be possible in those situations where Schema R holds. On the other hand, neither philosophical nor “physical” reduction seems possible when the limiting correspondence relation between the theories is singular. Perhaps in such cases it is best to speak simply of intertheoretic relations rather than reductions. It is here that much of philosophical and physical interest is to be found. This claim and the following discussion should not be taken to be anything like the received view among philosophers of science. Instead, they reflect the views of the author.