cogent vs syllogistic

cogent

adj
  • Appealing to the intellect or powers of reasoning. 

  • Forcefully persuasive; relevant, pertinent. 

  • Reasonable and convincing; based on evidence. 

syllogistic

adj
  • Of or pertaining to a syllogism. 

How often have the words cogent and syllogistic occurred in a corpus of books? (source: Google Ngram Viewer )