The need for understanding serves as a theme throughout social and personality psychology. It is reflected in people's striving toward a shared, social construction of reality (e.g., conformity, uniformity) that runs through so much of the history of theory and research in the field. Stemming from this core motivation, the literature is peppered with illustrations of the preeminence of certainty as a goal (e.g., clarity, consistency, consonance, and related constructs) and the ultimate objective of cultural consensus. Yet, the role of doubt in the form of shaky certainty about the basis for beliefs in attitudes -or doubts about one's self-esteem or self-concept -has increasingly taken center stage. This review takes the self-competence element (vs. self-liking element) of selfworth judgments as its focus and provides an integration of individual difference approaches and experimental investigations of self-doubt. Long neglected, self-doubt increasingly appears critical for understanding some of the surprising, ironic, and self-defeating cognitive, emotional, and behavioral findings seen in the achievement realm.Four be the things I'd been better without: Love, curiosity, freckles, and doubt Dorothy ParkerThe fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt Bertrand Russell Certainty and clarity are prized and desired, except when they aren't. A careful search for pithy quotations about the value of clarity reveals little, while the virtues of doubt are widely praised. Yet, the preeminence of certainty and clarity as a core human social motive (among social and personality psychologists) is revealed in the central spot accorded the need to understand (e.g., Fiske, 2004). People are said to wish to know things quickly and clearly and to predict things well enough to function in ordinary daily social life (e.g., Heider, 1958). The value of the shared, social construction of reality can be traced through the Festinger tradition (e.g., 1950, 1954, 1957) where disunity among people is psychologically uncomfortable and produces pressures toward uniformity (1950), lack of certainty produces social information seeking (i.e., affiliation) driven by the desire for clarity (1954), and ultimately one's own beliefs and behavior push people away from dissonance and toward consistency of beliefs (1957); indeed, people sometimes place a premium on certainty, clarity, and consonance (a satisfying sense of reality) in the face of objective facts to the contrary. Dissonance is dismissed even when the facts are clearly in conflict and impossible to reconcile -as when prophesy fails (e.g., Gal & Rucker, 2010).People bother to make sense of themselves and one another (e.g., attribution; social cognition) to satisfy this core motive of understanding, setting the stage for the important Social and Personality Psychology Compass 6/6 (2012):