The New Palgrave Dictionary of Economics Online

Mill approached economic theory using conceptual and verbal analysis. This worked well for settled truths applied to circumscribed situations, such as a rise in the ratio of food prices to manufactured goods prices under growth subject to decreasing returns. He needed, but did not develop, a different method for multi-causal problems. Mill insisted that value and production were settled areas of political economy but was open to societal reforms that would result in altered shares of income and wealth. This distracted from the coherence of his Principles of Political Economy and from his reputation as a theorist, while ensuring that he will be remembered for challenging readers to entertain breathtaking prospects for human improvement.