ABSTRACT
Perhaps the definition of measurement in terms of number assignment according to mathematical rules makes sense in the abstract world of mathematics, but it does not in the empirical world unless the rules specify what the numbers are of, namely , the physical units of measurement. True enough, we find in , forgive me, Encyclopedia Britannica (1958, Vol. 15 , p. 135) that measurement is " the determination of the magnitude of anything in terms of a suitable unit. " The author of the article adds : " Such units may be quite arbitrary ." Numbers are not even mentioned. Of course , they are implied-after we have defined arbitrarily the magnitude of a unit , we count how many units have to be added together to match the magnitude of whatever we are measuring. Numbers refer simply to the numerosity of the units. They change every time the units change . How essential , then , are numbers in the fundamental operation of measurement? A simple example may guide us to an answer.
