I dreamt last night that weight was bread. More precisely, I dreamt that a kilogram was a loaf of dark, rye-like, round bread, about the diameter of a steering wheel. I do not mean that the loaf represented the kilogram, or stood in for it conceptually, in the way that, say, an anatomical foot originally stood in for a unit of length. I mean that such a loaf is just what a kilogram was.
I was in some sort of shop, and the shopkeeper was trying to weigh something out for me on an old-fashioned scale. He kept having to remove whatever it was we were trying to weigh, and replace it with the loaves of bread. Since the loaves just were weight, only they could give any reading at all on a scale.
Plot-wise the dream was a bit thin, but it raised an important conceptual problem. It is as if the creation of a unit of measurement initiates a process of reification that, in its final stage, has us thinking about the unit as a definite, property-rich entity. I recall reading somewhere that some embarrassingly high number of Americans believe that calories exist in the same way marbles or eggs do: like little invisible pellets scattered in the food that makes people fat. And in turn the holy grail of the diet industry –a calorie-free fat substitute– is conceptualized as fat with the little pellets removed.
This neo-corpuscularianism can perhaps be seen more charitably if we recall that thing-hood is already contained within the concept of unit, a word which in many languages is identical to unity (e.g., Einheit, unité, единство). As Leibniz for one well understood, being and unity are practically the same. A Leibnizian corollary would also have it that whatever is not a thing is not really a unit(y) either, and further anything that is arbitrarily constituted cannot qualify as a thing. Nothing is more arbitrarily constituted than a so-called unit of measurement: there is absolutely no reason why a foot should not be three inches longer or shorter, and moreover nothing at all prevents us from conceptualizing fractions of these units.
So in effect we are being asked to conceptualize an impossible thing –units without unity– when we are asked to think about kilograms and feet and calories, and it may be that I, in my dream of the loaves, or the ignorant Americans polled on their dietetical knowledge, are in our mistake simply correcting something that was conceptually garbled to begin with.