S: (adj) fair, just (free from favoritism or self-interest or bias or deception; conforming with established standards or rules) "a fair referee"; "fair deal"; "on a fair footing"; "a fair fight"; "by fair means or foul"
S: (adj) logical (capable of or reflecting the capability for correct and valid reasoning) "a logical mind"
S: (adj) rational (consistent with or based on or using reason) "rational behavior"; "a process of rational inference"; "rational thought"
S: (adj) valid (well grounded in logic or truth or having legal force) "a valid inference"; "a valid argument"; "a valid contract"
S: (adj) commonsense, commonsensible, commonsensical (exhibiting native good judgment) "arrive home at a reasonable hour"; "commonsense scholarship on the foibles of a genius"; "unlearned and commonsensical countryfolk were capable of solving problems that beset the more sophisticated"
S: (adj) healthy, intelligent, levelheaded, level-headed, sound (exercising or showing good judgment) "healthy scepticism"; "a healthy fear of rattlesnakes"; "the healthy attitude of French laws"; "healthy relations between labor and management"; "an intelligent solution"; "a sound approach to the problem"; "sound advice"; "no sound explanation for his decision"