If the price of tacos doubles, and the price of toilet paper halves, in a universe with only those two commodities, what is inflation? It's (2, 0.5). You coul

If the price of tacos doubles, and the price of toilet paper halves, in a universe with only those two commodities, what is inflation? It's (2, 0.5). You could turn this into a scalar if you want to. But you have to throw away information to do so. Or, to put it another way, you have to select a subset of the information. You can't interpret the inflation vector as a direction, because inflation space is not a metric space (or something - the particular genre of vector spaces where geometric concepts are meaningful).