mindmap root((合理)) valid implies being supported by objective truth or generally accepted authority: absence will be excused for ~ reasons. sound implies a basis of flawless reasoning or solid gounds: a ~ proposal for combatting terrorism. cogent may stress either weight of sound argument and evidence or lucidity of presentation: the prosecutor's ~ summation won over the jury. convincing suggests a power to overcome doubt, opposition, or reluctance to accept: a documentary that makes a ~ case for court reform. telling stresses an immediate and crucial effect striking at the heart of a matter and may or may not imply soundness and validity: a ~ example of bureaucratic mentality.