The view of human agency that inhabits economics. With the hegemony of neo-classical economics in the last half of the 20th century, homo economicus has been understood as a rational maximizer (i.e., decisions reflect the optima of an underlying objective functions subject to constraints). Profit and utility maximization are just aspects of this. Almost ever since this view of ecomomic agency was born in the 19th century, it has come under criticism for its unrealism. Critics have suggested that mental limitations and limited information effectively prohibit humans from finding the optimum of their objective functions (for example, firms, the maximum of their profit function). Instead, it is suggested that agents rely on various rules of thumb. There is a wide body of survey research evidence that firms do not use profit maximizing rules to set prices and quantities to produce. In addition, recent experimental evidence has found widespread departures from utility maximization. This experimental evidence has helped to lead to the emergence of what has become to be known as behavoral economics, wereby humans are taken to act quasi-rationally (decision making reflects numerous inconsistencies and departures from optima). Still at an early stage of development, behavoural economics has strong simularities to a larger body of heterodox economics (non-neoclassical) that has been built up on a view of the human agent as quasi-rational and employing various rules of thumb (for example, firms set prices using a mark-up over cost) to make decisions.