He published several of his lectures. In his Two Lectures on the Checks to Population (1833) he introduced the parable of "The Tragedy of the Commons" (whose theme was later to be developed by the ecologist Garrett Hardin). Lloyd observed that when pastureland is (the "commons") is available to all, cattle-owners have a short-term interest in increasing the size of their herds. But, unchecked, the size of the herds on the commons will soon exceed its carrying capacity. The commons will be doomed by overgrazing. The argument was used by Lloyd to dispute Adam Smith's idea of the "invisible hand". Some modern economists argue that the problem can be "solved" by assigning private property rights to the field.

In his Lectures on Population, Value, Poor Laws and Rent (1837) he introduced a concise and complete statement of the concept of diminishing marginal utility, and connected demand to value, but he presents neither derivation nor elaboration. Still this contribution places him clearly in the ranks of the Oxford-Dublin school of proto-Marginalists.

Major Works of William F. Lloyd

• Lecture on the Notion of Value, as distinguished not only from utility, but also from value in exchange, 1833.
• Two Lectures on the Checks to Population, 1833.
• Four Lectures on Poor-Laws, 1835
• Two Lectures on the Justice of the Poor-Laws and One Lecture on Rent, 1837.
• Lectures on Population, Value, Poor Laws and Rent, 1837.

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