Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Robert Kelly is managing director of XTS ...

Discover the Diamond-Water Paradox—why diamonds cost more than water. Learn about subjective value and marginal utility in economic valuation.

George Gilder and Gale Pooley rightly note that a useful measure of how much things cost is how long we must work to earn enough to purchase them (“We Should Measure Prices in Time,” op-ed, April 17).

Karl Marx’s economic theory is founded on the labour theory of value. In Marx’s Theory of Value at the Frontiers, Güney Işıkara and Patrick Mokre make a valuable contribution to Marxist economics, ...

Smith’s theory of value and distribution, which emphasizes labor time as the determinant of prices, has been widely misunderstood. Ricardo misinterpreted it as relevant only to primitive societies, ...