First-Order Logic:

There's Reasoning, and then There's Reasoning

As humans, we have always prided ourselves on our capability to think things by: to reason things out and come to the only conclusion possible in a Sherlock Holmes kind of approach. However what accurately do we mean by "reasoning" and can we automate this process?
So we can take Sherlock Holmes as a case study for describing altered types of reasoning. Assume after solving another major case, he says to Dr. Watson: "It was elementary my dear Watson. The killer always left a silk glove on the scene of the murder. That was his calling card. Our investigations are showed that there is only three people have purchased such gloves in the past year. So we considered after that the Professor Doolally and Reverend Fisheye have iron-clad alibis, that can be the murderer must have been Sergeant Heavyset. In fact he just tried to murder us with that umbrella, we discern we had our man."