Logos is just one of the many things the rhetor must consider when forming an effective argument. The key to evaluating arguments is distinguishing the valid from the invalid ones. Socrates is a man. Socrates is mortal. The flower is a plant.
All weeds are flowers.
If A implies B and A is true, then B is true. If A implies B and B is false, then A is false. The most common type of deductive logic is a syllogism which will be discussed further on in the paper. A syllogism, as I mentioned earlier, is the most common type of deductive logic. These books were printed in 1660.