While this post uses a biology metaphor for currency, I have been thinking about a mathematical metaphor.

For a whole bunch of reasons I’m going to skip over right now, mathematicians have one very abstract field of study called category theory, which studies different things that can happen when you draw an arrow from one thing to another. (I told you it was abstract.) Sometimes they will reverse the direction of the arrows, and start proving new things.

At any rate, I’ve started to think about arrows when I think about currencies in the broad sense of markers which allow you to do stuff: dollars, bus tickets, poker chips, school grades and degrees. They aren’t real things, but some of them allow you to demand someone make you a sandwich, get on a vehicle, make bets, or access further learning* or a profession.

It’s not interesting that the markers look different, or that some markers are virtual tickmarks in a debit account or guild bank instead of being represented physically. But it is interesting that they seem to behave in different-yet-similar ways. They all allow you to do something, but they all have limits on what that something is. Some are meaningless if they cannot be transferred; others cannot be transferred at all. What is always, sometimes, or never the same in two distinct currencies?

* The nature and existence of this, obviously, is going to get very interesting in the new information ecosystem.