These words indicate an intelligent and objective approach to problems or behaviour that is temperate, fair and sound. Sensible puts less emphasis on intelligence than on common sense; it suggests an attitude that is prudent, calmly controlled, considerate, understanding and aware of consequences by virtue of distilled experience: the few sensible men who refused to indulge in the foolish fads of the day; a sensible approach to a controversial subject; the plain, sensible people who are the backbone of the nation. Reasonable is similar to sensible in emphasizing the value of distilled experience; but its connotations are slightly different in suggesting an approach or situation that is fair, just, objective or unemotional in its avoidance of extremes: a reasonable price; reasonable neighbours who did not object to the occasional parties he held; asking his son to be reasonable about his demands for the family car. Oddly enough, rational rather than reasonable is the word here that is most emphatic about the value of reason as a guide; this contrasts with the stress on experience implied by the previous words. Most specifically, it points to a problem-solving process of thinking that employs valid or logical methods in reaching conclusions: a rational way of going about the vast tasks involved in city planning; a rational explanation for the enigmatic events surrounding the catastrophe. Rational may also indicate a coherent mind, one that is not mentally unbalanced or at the mercy of overpowering emotions: becoming more rational as the tranquillizer took effect; psychiatrists who debated if the accused man was rational enough to stand trial.

Lucid and sane are both directed to this last meaning of rational . Lucid indicates a mind free of internal pressures or distortions: lucid intervals between bouts of catatonic depression. It can refer to a rational approach or train of thought that is particularly clear, understandable of helpful in its simplicity: a lucid argument against the theories advanced in the article. Sane is commonly used in both ordinary speech and legal terminology to refer to someone who is not psychotic, but the word has no usefulness to psychologists: declared to have been sane at the time of the murders; struggling to stay sane in a mad world. Sane also has a use akin to reasonable in referring to a fair, just or sensible approach: sane legislation to deal with an increasingly urgent problem; sane attitudes towards disciplining their children.