Now that you know what a logical syllogism is, let’s look a little more closely at how they are constructed. Logicians have developed six fairly basic rules for constructing valid syllogisms. Although they may be stated in many different ways, essentially these "Rules" are as follows:



  Basic “Rules” for Constructing Logical Syllogisms

Rule 1: All syllogisms must contain three terms: a major term, a minor term and a transitory (or middle) term.

Rule 2: The transitory term must be “distributed” in at least one premise (either the major premise or the minor premise).

Rule 3: The conclusion cannot contain any term that is not “distributed” in at least one premise (either the major premise or the minor premise).

Rule 4: A syllogism cannot contain two negative premises.

Rule 5: If either premise in a syllogism is negative, the conclusion must also be negative.

Rule 6: A syllogism with two universal premises (both the major premise and the minor premise) cannot have a particular conclusion.