Sherlock Holmes employs a peculiar type of method in his work, a method that sets him apart from his sometimes colleagues in the regular police force and also from the common man. He calls this method deduction and the use of deduction is a common themes running through every single Sherlock Holmes story. In logic, deduction is the inference of a conclusion from premises such as the inference of the fact that Socrates is mortal given the information that Socrates is a man and also that all me are mortal. This method differs from induction, which involves amassing separate instances, or facts and attempting to draw regular conclusions from them that often hold but that is not logically required to hold.