Theory underlying public choice analysis.
The behavior of individuals, groups and institutions can be understood as a series of rational choices designed, in an analogy with economics, to maximize their utility.
Patrick Dunleavy, Democracy, Bureaucracy and Public Choice (London, 1991)
Rational choice theory, also known as theory of rational choice, choice theory or rational action theory, is a framework for understanding and often formally modeling social and economic behavior. The basic premise of rational choice theory is that aggregate social behavior results from the behavior of individual actors, each of whom is making their individual decisions. The theory also focuses on the determinants of the individual choices (methodological individualism). Rational choice theory then assumes that an individual has preferences among the available choice alternatives that allow them to state which option they prefer. These preferences are assumed to be complete (the person can always say which of two alternatives they consider preferable or that neither is preferred to the other) and transitive (if option A is preferred over option B and option B is preferred over option C, then A is preferred over C). The rational agent is assumed to take account of available information, probabilities of events, and potential costs and benefits in determining preferences, and to act consistently in choosing the self-determined best choice of action. In simpler terms, this theory dictates that every person, even when carrying out the most mundane of tasks, perform their own personal cost and benefit analysis in order to determine whether the action is worth pursuing for the best possible outcome. And following this, a person will choose the optimum venture in every case. This could culminate in a student deciding on whether to attend a lecture or stay in bed, a shopper deciding to provide their own bag to avoid the five pence charge or even a voter deciding which candidate or party based on who will fulfill their needs the best on issues that have an impact on themselves especially.
Rationality is widely used as an assumption of the behavior of individuals in microeconomic models and analyses and appears in almost all economics textbook treatments of human decision-making. It is also used in political science, sociology, and philosophy. Gary Becker was an early proponent of applying rational actor models more widely. Becker won the 1992 Nobel Memorial Prize in Economic Sciences for his studies of discrimination, crime, and human capital.
A particular version of rationality is instrumental rationality, which involves seeking the most cost-effective means to achieve a specific goal without reflecting on the worthiness of that goal.
Rational choice theorists do not claim that the theory describes the choice process, but rather that it predicts the outcome and pattern of choices. An assumption often added to the rational choice paradigm is that individual preferences are self-interested, in which case the individual can be referred to as a homo economicus. Such an individual acts as if balancing costs against benefits to arrive at action that maximizes personal advantage. Proponents of such models, particularly those associated with the Chicago school of economics, do not claim that a model’s assumptions are an accurate description of reality, only that they help formulate clear and falsifiable hypotheses. In this view, the only way to judge the success of a hypothesis is empirical tests. To use an example from Milton Friedman, if a theory that says that the behavior of the leaves of a tree is explained by their rationality passes the empirical test, it is seen as successful.
Without specifying the individual’s goal or preferences it may not be possible to empirically test, or falsify, the rationality assumption. However, the predictions made by a specific version of the theory are testable. In recent years, the most prevalent version of rational choice theory, expected utility theory, has been challenged by the experimental results of behavioral economics. Economists are learning from other fields, such as psychology, and are enriching their theories of choice in order to get a more accurate view of human decision-making. For example, the behavioral economist and experimental psychologist Daniel Kahneman won the Nobel Memorial Prize in Economic Sciences in 2002 for his work in this field.
Rational choice theory has become increasingly employed in social sciences other than economics, such as sociology, evolutionary theory and political science in recent decades. It has had far-reaching impacts on the study of political science, especially in fields like the study of interest groups, elections, behaviour in legislatures, coalitions, and bureaucracy. In these fields, the use of the rational choice theory to explain broad social phenomena is the subject of controversy.
Human action that is in rational choice theory has been described as outcome of two choices. First, those feasible region will be chosen within all the possible and related action. Second, after the preferred option has been chosen, the feasible region that has been selected was picked based on restriction of financial, legal, social, physical or emotional restrictions that the agent is facing. After that, a choice will be made based on the preference order. 
The concept of rationality used in rational choice theory is different from the colloquial and most philosophical use of the word. Colloquially, “rational” behaviour typically means “sensible”, “predictable”, or “in a thoughtful, clear-headed manner.” Rational choice theory uses a narrower definition of rationality. At its most basic level, behavior is rational if it is goal-oriented, reflective (evaluative), and consistent (across time and different choice situations). This contrasts with behavior that is random, impulsive, conditioned, or adopted by (unevaluative) imitation.
Early neoclassical economists writing about rational choice, including William Stanley Jevons, assumed that agents make consumption choices so as to maximize their happiness, or utility. Contemporary theory bases rational choice on a set of choice axioms that need to be satisfied, and typically does not specify where the goal (preferences, desires) comes from. It mandates just a consistent ranking of the alternatives.:501 Individuals choose the best action according to their personal preferences and the constraints facing them. E.g., there is nothing irrational in preferring fish to meat the first time, but there is something irrational in preferring fish to meat in one instant and preferring meat to fish in another, without anything else having changed.