What Kevin Drum wants is simply not possible.

All that conceded, we really should be able to agree on a good, general-purpose inflation measure. We can still have lots of different measures for specialized purposes, but the headline inflation rate should be something that, say, 90 percent of economists can agree about.

Inflation for whom? Should we be using the GDP Price Deflator vs. the CPI? If so, why? If not, why not? If we use the CPI, what basket of goods should we use? How do we account for quality changes over time? Is there any accounting for housing costs? House prices are not included in the CPI, by the way — just rent. (Or rather, “rental equivalence,” which is too technical to get into here — start here for more info. This is largely a better way of doing it I agree, but its failure states need to be recognized.)

Different people at different times also themselves buy a very different basket of goods. Persons 18-30 consume educational products at a much higher rate than those purchased by the 60-80 set, thus their basket of goods mix is very different and thus the actual inflation rate they encounter is also very divergent. By the same token, if medication and medical expense is taken into account, inflation for 70-year-olds will be de facto much higher.

And poor people are much more affected by price changes in necessities like food, heating/cooling and electricity (etc) costs than those that are richer. This leads to the consideration of weighting, as in what weighting do we use and how do we decide this? Is there any one best weighting? Of course there is not.

Beyond this, there are also the more philosophical and epistemological questions of the simple incommensurability of comparing inflation over time intervals long enough where culture has changed significantly. Over such periods, the old measure was in fact ascertaining something completely different — for instance, what does inflation mean when most women weren’t working full-time jobs, as compared to now when most women are? Or when a car was not a necessity, but now it is in the vast majority of America?

In short, contra Drum (as I often am), inflation cannot be measured by any one number, and doing so leads often to absurdity. It is an idea more than an actuality, and it cannot be divorced either from its cultural context or other considerations such as for whom are we doing the measuring and why.