From the Greek “syllogizisthai,” meaning “to infer,” a syllogism is a way of making an argument that involves a specific format: a major premise, a minor premise, and a conclusion. The conclusion logically follows from the preceding premises. This form of coming to conclusions is also known as deductive reasoning. The fictional detective Sherlock Holmes was known for his powers of deductive reasoning. A classic syllogism is demonstrated in the story “A Study in Scarlet.” The major premise: All men who wear boots with London clay on them have recently walked on London streets. The minor premise: This man’s boots have London clay on them. The conclusion: This man has recently walked on London streets.