Alexander the Great is not a god: this is a Mediate Inference.

The evidence consists of two propositions connected by the term 'man,' which is common to both (a Middle Term), mediating between 'gods' and 'Alexander.' Mediate Inferences comprise Syllogisms with their developments, and Inductions; and to discuss them further at present would be to anticipate future chapters.

We must now deal with the principles or conditions on which Immediate Inferences are valid: commonly called the "Laws of Thought." Sec.3.The Laws of Thought are conditions of the logical statement and criticism of all sorts of evidence; but as to Immediate Inference, they may be regarded as the only conditions it need satisfy.

They are often expressed thus: (1) The principle of Identity--'_Whatever is, is_'; (2) The principle of Contradiction--'_It is impossible for the same thing to be and not be_'; (3) The principle of Excluded Middle--'_Anything must either be or not be_.' These principles are manifestly not 'laws' of thought in the sense in which 'law' is used in Psychology; they do not profess to describe the actual mental processes that take place in judgment or reasoning, as the 'laws of association of ideas' account for memory and recollection.

They are not natural laws of thought; but, in relation to thought, can only be regarded as laws when stated as precepts, the observance of which (consciously or not) is necessary to clear and consistent thinking: e.g., Never assume that the same thing can both be and not be.
However, treating Logic as the science of thought only as embodied in propositions, in respect of which evidence is to be adduced, or which are to be used as evidence of other propositions, the above laws or principles must be restated as the conditions of consistent argument in such terms as to be directly applicable to propositions.