Motivated reasoning is a pervasive force in politics. The concept of motivated reasoning was developed and elaborated in both psychology and economics as a way of understanding the way in which people learn and respond to information, and as a mechanism to explain behavior that is seen as less than optimal. It has been important in political science since the early 2000s. Political scientists initially connected the distinct constructs of motivated reasoning with online information processing, given the affective, unconscious, and automatic bases of both processes, but they later distinguished cognitive effort and processing style from underlying goals or motivation. Most research on motivated reasoning in political science focuses on two primary motivations: accuracy and directional goals. An accuracy motivation is defined by reasoning that seeks to arrive at a conclusion that is free from error given the information at hand, whereas a directional goal is defined by a desire to protect one's existing beliefs or identities. Much of the early research on motivated reasoning in political science painted citizens as incapable of evaluating information objectively, and, to make matters worse, citizens' processing biases appeared to increase with political knowledge, interest, and the strength of existing political beliefs. A second generation of research on motivated reasoning identified individual-level and contextual factors that moderated or eliminated directional biases. Scholars developed a better understanding of how motivations rooted in partisan identity affect information interpretation, evaluation, and decision-making, as well how different information environments can shift the motivations that citizens pursue when they are reasoning about politics. The pursuit of an accuracy motivation in political reasoning is now considered a realistic and attainable standard for evaluating citizen competence in democratic societies that avoids many of the pitfalls of past attempts to define the quality of citizens' reasoning capacities.