In order to break the force of all reasonings respecting the inherent incredibility of the Trinitarian doctrine, the principle has been frequently advanced, that a statement which would be contradictory, if made respecting an object _within reach_ of our knowledge, cannot be affirmed to be so, if applied to an object _beyond_ our knowledge; since in the one case _we have_, in the other _we have not_, some experience to guide our judgment, and serve as a criterion of truth. Thus, it is said, to affirm of man, that his nature comprises more than one personality, might, without presumption, be pronounced a contradiction; because we are familiar with his constitution; but knowing nothing of the mode of God’s existence, except what he is pleased to reveal, we cannot prove the same statement to be contradictory, when made respecting _his_ essence. This rule, like all the Trinitarian reasonings on this subject, derives its plausibility from an ambiguous use of terms. It has _one sense_ in which it is true, but inapplicable to this subject; and _another_, in which it is applicable, but false. The rule is sound or unsound, according to the meaning which we assign to the word _contradiction_; a word which, in other arguments besides this, has made dupes of men’s understandings. There are obviously two kinds of contradiction:—one relating to _questions of fact_, as when we say, it is contradictory to experience that ice should continue solid in the fire; the other, relating to questions of mere _thought_, as when we say, it is contradictory to affirm that force is inert, or that the diameters of a circle are unequal. The former of these suggests something _at variance with the established order of causes and effects_, and constitutes _a natural or physical_ impossibility; the latter suggests a _combination of irreconcileable ideas_, constituting a _logical or metaphysical impossibility_, or more properly, a _self_-contradiction.