science alone, for example, cannot prove that it is bad to enjoy the infliction of cruelty.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“I have also no doubt that, by these methods, many ancient problems are completely soluble. There remains, however, a vast field, traditionally included in philosophy, where scientific methods are inadequate. This field includes ultimate questions of value; science alone, for example, cannot prove that it is bad to enjoy the infliction of cruelty. Whatever can be known, can be known by means of science; but things which are legitimately matters of feeling lie outside its province. Philosophy, throughout its history, has consisted of two parts inharmoniously blended:” source