phrase most often heard is "competing paradigms," which is a reductio ad
absurdam, since if they are competing, neither of them is a paradigm --
i.e., neither can be associated with normal science. (Kuhn could have
made this clearer. But I think it's inescapable from the logic of his
That is a reasonable argument, but I do not think that the error is logical. After all, in the early days of The Scientific Revolution, Newtonianism and Cartesianism really were competing paradigms.
I think there can be "normal science" in a particular tendency in a nonconsensual field--evem philosophy! But may Lakatos' talk of reserach programmes is more usual in this context.