The ambiguous middle term.

Light is contrary to darkness;

Feathers are light; therefore

Feathers are contrary to darkness.

The inaccuracy arises out of the fact that the word 'light' has two

meanings; and shows most forcefully the necessity for a definition of terms

before an argument is begun.

The undistributed middle term

White is colour;

Black is colour;

therefore Black is white.

Here the use of the word 'colour' is misleading.

The illicit process of the major

All quadrupeds are animals;

A bird is not a quadruped; therefore

It is not an animal.

This is a case of the illicit process of the major term, and the

inaccuracy arises from the employment of the whole of the term 'animal' in

the conclusion, when only a part of it has been employed in the premisses.

'No term must be distributed in the conclusion which was not distributed in

one of the premisses'.

From negative premisses nothing can be inferred

A fish is not a quadruped.

A bird is not a quadruped.

No further step can be taken.

If one premiss be negative, the

conclusion must be negative.

There are nineteen forms or figures in which syllogisms may appear, but

all valid argument admits of being stated in the first of these figures with

its four moods.  As we are not writing for students of logic, but simply to

help the student of Scripture, we shall not burden the reader with an

explanation of these nineteen figures, but will deal only with the first of

The first mood is suited to the discovery or proof of the properties of

a thing.  Its construction is as follows:

All B is C ... All Scripture is inspired (2 Tim. 3:16).

All A is B ... Paul's epistles are Scripture (2 Pet. 3:16).

All A is C ... Paul's epistles are inspired.

The best illustration of this mood is three concentric circles, the

largest being C, the next B and the smallest A.