“While we may say that the essentialist interpretation reads a definition normally, that is to say, from the left to the right, we can say that a definition, as it is normally used in modern science, must be read back to front, or from the right to the left; for it starts with the defining formula, and asks for a short label to it. Thus the scientific view of the definition A puppy is a young dog would be that it is an answer to the question What shall we call a young dog? rather than an answer to the question What is a puppy?. (Questions like What is life? or What is gravity? do not play any role in science.) The scientific use of definitions, characterized by the approach from the right to the left, may be called its nominalist interpretation, as opposed to its Aristotelian or essentialist interpretation. In modern science, only nominalist definitions occur, that is to say, shorthand symbols or labels are introduced in order to cut a long story short. And we can at once see from this that definitions do not play any very important part in science. For shorthand symbols can always, of course, be replaced by the longer expressions, the defining formula, for which they stand. In some cases this would make our scientific language very cumbersome; we should waste time and paper. But we should never lose the slightest piece of factual information. Our scientific knowledge, in the sense in which this term may be properly used, remains entirely unaffected if we eliminate all definitions; the only effect is upon our language, which would lose, not precision, but merely brevity. (This must not be taken to mean that in science there cannot be an urgent practical need for introducing definitions, for brevitys sake.) “ Karl Popper, The Open Society and Its Enemies, Chapter 11.
Posted on: Thu, 10 Apr 2014 03:30:00 +0000