Metaphors frame our understanding of numbers. The idea of per capita is one such. To use per capita in your arguments is to suggest that each of us is metaphorically associated with a “fair share” of something. For instance, I once read somewhere that the money spent on a typical American child was 30 times that spent on an Indian child, which in turn, was 30 times that spent on a Somalian child. Whether you are inclined to agree or argue (“yeah, that seems roughly right” or “the real disparity is much worse” or “it isn’t so bad if you look at purchasing power parity”), you’ve been trapped by the metaphor. It has stopped you from questioning whether per capita is a useful frame of reference.
I encountered another example in the ABC show Over a Barrel: The Truth about Oil. One of the talking heads, T. Boone Pickens, offered this thought: the US has only 4% of the world’s population, but uses 25% of its oil production.
Let me juxtapose a different metaphor: the human brain constitutes roughly 2% of the body weight of an average adult, but uses 20% of the body’s oxygen supply. I am suggesting, of course, that the metaphor of the world as a giant organism is the appropriate one here, and that America’s disproportionate energy consumption might be justifiable on the basis of its role as the “brain” within the body politic of the world.
I am not actually making this argument right now. I am merely wondering: to what extent are our ideological commitments hidden within our choice of metaphors?
[#2 in my short-posts experiment. 274 words]