The conclusion of this letter is that consumers are not truly benefiting from advances in agricultural technology. The author concedes that, on the average, consumers are spending a decreasing proportion of their income on food. But the author contends that this would happen without advances in agricultural technology. The author reasons that demand for food does not rise in proportion with real income, so as real income rises, consumers will spend a decreasing portion of their income on food. This argument turns on a number of dubious assumptions.
First of all, while asserting that real incomes are rising, the author provides no evidence to support this assertion; moreover, it might be false. Even if salaries and wages go up, this fact may not indicate that real income has increased proportionally. Real income takes into account any effect inflation might have or, the relative value of the dollar. It is possible that, when salaries and wages are adjusted for inflation, what appear to be increases in real income are actually decreases.
In addition, the author assumes that increases in real income explain why, on the average, consumers are now spending a decreasing proportion of their income on food. But no evidence is provided to show that this explanation is correct. Moreover, the author fails to consider and rule out other factors that might account for proportional decreases in spending or food.