For one thing, it does not know the difference between reality and fantasy. Or the products of our imagination which are often the same thing. The subconscious also works differently from the conscious mind because one of the really important jobs of the subconscious is to keep subconscious processes sub- or un conscious. That is, secret from the conscious mind. But first let's tackle this business of logic.
Deductive logic is the process of reasoning from the general to the specific.
There isn't anything difficult about this process if you remember that deductive logic means applying what you know about a lot of things to one or just a few things that are similar. For instance, just about every human being you've ever known or heard about was born with eyes. So when you hear that someone gave birth to a new baby, it is through deductive logic that you assume that that new baby also has eyes. To make another example, consider the case of redheads. An unsubstantiated stereotype has it that redheads are hot tempered.