Journal: Journal of the Evangelical Theological Society
Volume: JETS 25:2 (Jun 1982)
Article: Gordon H. Clark And The Laws Of Thought
Author: John V. Dahms

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JETS 25:2 (June 1982) p. 233

Gordon H. Clark And The Laws Of Thought

John V. Dahms*

In JETS (June 1981) 163–171, Gordon Clark makes a critical appraisal of a volume by Mark Hanna. It is not our purpose to enter that debate but only to consider Clark’s statement on p. 168 to the effect that the law of contradiction and the law of identity are really the same law. What he actually says is this: “If truth is a logical system, its first axiom must be the law of contradiction, or of identity, which is really the same thing.1

What prompts Clark to think that the law of contradiction and the law of identity are “really the same thing” I do not know. It is possible that the ambiguity of a common way of stating the law of contradiction could lend credence to such a view. I refer to this formulation: “Nothing can be both A and not-A.” If “not-A” is understood to mean simply “the absence of A,” then of course the law of contradiction is really the same as the law of identity (“If anything is A, it is A.”). And in this connection it may be noted that Aristotle, Metaphysics, to which Clark refers twice on p. 167, states that “privation is a kind of contradiction.”2

But Aristotle thought—and everyone agrees, so far as I know—that the law of contradiction implies more than the absence of A. He argued that the law of contradiction must be true, otherwise one could affirm that “the same thing (is) a trireme, a wall, and a man.’ “3 This means, however, that the law of contradiction is not identical in meaning with the law of identity. The law of identity simply implies that if you have a trireme, you have a trireme; if you have a wall, you have a wall; if you have a man, you have a man. It says nothing about it being impossible for the same thing to be all three at the same time. It is only the law of contradiction that disallows the judgment that the same thing can be all three at the same time. “Not-A” in the law of contradiction cannot mean simply the absence of A, if that law has the significance commonly if not always accorded to it. It must mean “a positive contrary of A.” And to say that the law of identity and the law of contradiction are “really the same thing” is quite unwarranted.

In this connection it may be noted that the law of contradiction assumes the

*John Dahms is professor of New Testament at Canadian Theological College in Regina, Saskatchewan.

JETS 25:2 (June 1982) p. 234

law of identity. Only if A is A, and not-A is not-A, does the law of contradiction have validity. In other w...

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