Grain and taxation

Why did early states tax grain when tubers and livestock fed their people just as well?

Wheat, barley, rice, millet, maize: the early fiscal systems of Mesopotamia, Egypt, China and Mesoamerica all ran on cereal. Yet the people in those places also ate roots, pulses, fish and meat, and in several regions tubers yield more calories per unit of land than grain does. If the point of a tax is to feed an army and a court, why should the state care which food it takes? The answer has less to do with nutrition than with what an official standing at the edge of a field can find out.

Put yourself in the collector's position, and notice that his hard problem is not force. He may have soldiers. What he lacks is knowledge. He must arrive knowing roughly what is owed, because if he arrives ignorant the cultivator sets the figure and he cannot contradict it. A tax system is, before anything else, a way of making a stranger's wealth estimable from outside.

So what must a crop do to be estimable? Take the conditions one at a time and watch which foods fall away.

First, it should be countable at a single moment. Cereals ripen on a known date and must be cut within a short window, so the entire year's yield passes through one place — the threshing floor — in a heap, outdoors, in the open. A potato or a yam instead stays in the ground and is dug as it is wanted, over months. There is no heap and no moment; a collector arriving in a field of them is looking at soil.

Second, it should be assessable before the fact, and this condition is both the most often missed and perhaps the strongest. Cereal is sown over measured ground, grows above the soil, and yields at a roughly predictable rate per unit area — so the expected take can be computed from the sown area alone, from a path at the field's edge, weeks before the harvest exists. The demand is fixed before the cultivator has any chance to hide anything. Land survey becomes possible, and with it a permanent register. Nothing comparable can be done with a root crop, whose yield is invisible until it is lifted.

Third, it should keep: grain in a dry granary lasts years, so the state can hold it across a bad season and spend it long after harvest. Fourth, it should be divisible and standard, a fixed volume of barley being much the same wherever measured — which is why grain became not merely the thing taxed but the unit of account and the ration itself, the substance in which wages and temple allowances were reckoned.

Now test the argument against livestock, which fails on a different condition from tubers. A herd is countable, stores itself, and even walks to the collector. But it can also walk away. A herder who sees an assessor coming over the ridge takes his wealth with him. That is not a defect of animals as such — it is a defect of animals belonging to mobile people. Where herds were penned and their owners settled, animals were taxed perfectly well, as tithes on lambs and wool and alms on herds both show. The variable is immobility of the owner, not the species of the beast.

Notice what this makes of the tax base: not the most productive crop nor the most nutritious, but the most visible. And a state that taxes what it can see puts pressure on what gets planted, because the cultivator's obvious countermove is to grow what cannot be assessed, or to leave for hills and marshes where nothing can be.

The claim is not that cereal is a superior food or that tuber-growers cannot be ruled. It is narrower: given an administration with almost no capacity to observe, cereal is the one staple whose quantity a stranger can estimate cheaply and in advance. Everything else follows.

Two complications keep the argument honest. It is not a law: the Inka state taxed labour rather than produce, kept its accounts on knotted cord, freeze-dried potatoes into chuño that warehoused for years, and ran a demanding fiscal system on a tuber base. What looks like an inherent property of the crop is better read as a cost a sufficiently developed administration can pay — where record-keeping is expensive the crop decides, where it is cheap the state has options.

And the causal direction is genuinely disputed. James Scott's version, in which grain makes the state possible, is influential and also criticised, partly because established states then forced cultivators onto cereal, so the correlation is fed from both ends.

One nearby question is worth marking off. Asking why farming societies produced rulers at all is a different problem, needing a second condition entirely — that people be unable to walk away. This question takes the state as given and asks only which of the foods in front of it a barely-literate administration could assess.

• How land survey and the written register changed what a state could demand, and from whom.
• Why populations under fiscal pressure so often shifted toward root crops, shifting cultivation, or the hills.

Every term the collection defines is gathered in the glossary.