How is Logic Evidence for God?
Logic is simply the science of reasoning and argumentation. In essence, the study of logic is concerned with inferences: what conclusions we should—or shouldn’t—draw from one or more premises (initial assumptions or claims). Logic distinguishes between good inferences (i.e., reliable forms of reasoning) and bad inferences (i.e., flawed forms of reasoning).
It might sound strange to suggest that logic itself could be evidence for God. Isn’t logic just a tool that people use to evaluate evidence for (or against) God or to construct arguments for (or against) God’s existence? Certainly. But the very fact that there are laws of logic, and our minds have access to such laws, is a truly remarkable thing. To say that there are laws of logic is to say that laws of logic really exist. But whatever they are, laws of logic cannot be material things, like subatomic particles or electromagnetic waves. The laws of logic don’t have physical properties like mass, electric charge, or spatial location. They are non-material, non-physical entities. The laws of logic have been aptly called laws of thought or laws of reason: they are norms or principles that govern thinking and reasoning.
But the laws of logic are not anything that we ourselves created or constructed. We don’t get to determine them or to change them. In a very significant sense, the laws of logic stand over us and are independent of us—which is just to say that the laws of logic transcend us. The laws of logic would exist even if I did not exist or you did not exist—indeed, they would be there even if no human beings at all existed. But it’s very hard to make sense of that fact in terms of a materialistic worldview, according to which there is no mind, reason, or intelligence behind the cosmos, and everything that exists is the product of undirected physical entities and processes. How could there be laws of thought even in the absence of any thinkers? How could laws of reason arise out of matter alone?
On the fact of it, transcendent laws of reason fit far better into a theistic worldview, according to which there is a transcendent rational mind behind the physical cosmos. A divine mind would have all the appropriate features to ground laws of thought: transcendence, immateriality, eternality, necessity, universality, and perfect rationality. On this view, the laws of logic can be understood as an expression of the rational orderliness of God’s own thoughts. Furthermore, if humans are created in the image of God, as the Bible teaches, then our minds would be fashioned by God to reflect—at a finite, creaturely level—the same rational orderliness (at least if those minds are used properly!). In short, according to a Christian theistic worldview, we are created to think God’s thoughts after him. Thus, the Christian worldview with its distinctive doctrines of God, creation, and human nature can account for (1) why there are laws of logic, (2) what ultimately grounds those laws, and (3) how our minds have access to those laws.
James N. Anderson, Ph.D. is Carl W. McMurray Professor of Theology and Philosophy and Academic Dean at Reformed Theological Seminary. An ordained minister in the Associate Reformed Presbyterian Church, his scholarly interests primarily lie in philosophical theology, religious epistemology, Cornelius Van Til, and Christian apologetics.
Professor Anderson's Recommended Further Reading on the Topic:
Reppert, Victor, C. S. Lewis’s Dangerous Idea: In Defense of the Argument from Reason
James N. Anderson & Greg Welty, “The Lord of Noncontradiction: An Argument for God from Logic,” Philosophia Christi 13:2 (2011).
James N. Anderson & Greg Welty, “In Defense of the Argument for God from Logic,” Evangelical Philosophical Society Blog (September 1, 2013).