Some Simple Forms of Inference

This chapter focuses on some simple inferences and explains what we can learn from them. Any proposition of the shortened form is known as a hypothetical proposition, and the first of its constituent propositions is known as its antecedent, the second as its consequent. A deductive inference with two premises is called a syllogism; and since one of the premises in the case we are considering is a hypothetical proposition, it is known as a hypothetical syllogism. Since only one of the premises is hypothetical, we may call it a mixed hypothetical syllogism. It is easy to see that there are just four forms of hypothetical syllogism of this sort.