Critical thinking is the analysis of available facts, evidence, observations, and arguments to form a judgment. The subject is complex; several different definitions exist, which generally include the rational, skeptical, and unbiased analysis or evaluation of factual evidence. Critical thinking is self-directed, self-disciplined, self-monitored, and self-corrective thinking and accordingly, a critical thinker is one who practices the skills of critical thinking or has been schooled in its disciplines. Richard W. Paul has suggested that the mind of a critical thinker engages both the intellectual abilities and personal traits necessary for critical thinking. Critical thinking presupposes assent to rigorous standards of excellence and mindful command of their use. It entails effective communication and problem-solving abilities as well as a commitment to overcome native egocentrism and sociocentrism.