Skip to content

Logic: An Interview with Vern Poythress

Interview by Matt Claridge–

Knowing that God in Christ died for my sins, rose on the third day, ascended to the right hand of the Father, and will one day return are pieces of information that requires faith and special revelation. I never would have come up with a story like that on my own. But 2+2=4? We don’t need any divine revelation to tell us that, right? Wrong, says Vern Poythress, author of Logic: A God-Centered Approach to the Foundation of Western Thought. Dr. Poythress has joined Credo again for an interview on this most basic of all human activities: thinking.

For most people, I imagine, the study of logic conjures up images of cold, calculating reasoning. You use the example of Spock from the TV series Star Trek. Is this a fair or accurate picture of “pure” logic?

A lot depends on what is meant by “pure logic.” On the basis of Scriptural teaching about God, I think that logic originates with God. Logic is an expression of God’s personal character as the Trinitarian God. We can say that logic is God’s self consistency, which is summed up in Christ, the second person of the Trinity. Christ as the Logos or the Word of God expresses the whole character of God, including God’s commitment in Trinitarian relationships to be faithful to himself. The Father is faithful to the Son and the Son to the Father, in the fellowship of the Holy Spirit. This faithfulness implies consistency with respect to God’s own character. This consistency is the source of logic. Logic is one aspect of God, inseparable from all the other aspects of his character.

Thus, logic in God is personal. There is no such thing as “pure” logic, if by that one means a logic that is purely formal and mechanical, isolated from the whole of who God is. And what about human beings? God made us in his image. So we as persons reflect the consistency of God at a finite level. Logicality belongs to us as persons, and again it is not isolatable from who we are as complete persons.

In the Star Trek series, Spock is a convenient representative character, because he represents a good deal of popular thinking about what it would mean to be “purely logical.” But as a character, Spock offers us a distorted picture. This picture reflects a larger cultural distortion that has tried to shut God out in its thinking about logic. The larger pattern of rebellious thinking tries to replace the personal God of Scripture with a mechanistic, impersonalistic substitute. “Logic” for many people means an impersonalistic principle or principles for reasoning.

We should ask whether logic is ultimately personal (from God) or impersonal (abstract rules or principles that are just “there” eternally). The answer to the question makes a difference even at a practical level, as to whether people can be whole. If by Christ’s redemption we are reconciled to him, we can be progressively healed. We can serve God with all our heart. Our minds and our rationality and our love for God can all be reinforcing one another. To love God in a deep sense means being logical, because we love God’s consistency. Conversely, to be logical is to be in tune with and therefore in love with the logic of God. We become whole people where logic and love are two sides of the same coin. But when we flee from God, we ourselves end up being split into incompatable “parts,” a logical part and an emotional, intuitive part, which then fight against one another. They fight because both have been disconnected from God and made into competing sources of authority–ultimately, competing idols.

As a presuppositionalist, you argue that the Bible is our starting point even for such a subject as logic. Many might counter that we must start with logic if we are to understand the Bible. Which comes first, the chicken or the egg?

Let me answer this question by filling in a larger context in which it can fit. God always exists. He comes first. He created us in his image. As an aspect of his act of creation, he gives us reasoning ability, which reflects on a finite level his “logic,” his eternal self-consistency expressed through the Logos, the Word of God. The Bible is the word of God, and so it expresses who God is, including his consistency. That original consistency of God is in harmony with our sense of consistency in our subjectivity. And it is also in harmony with the consistency that we can see displayed in the world about us. People familiar with John Frame’s writings will recognize here the use of three of Frame’s perspectives: in the “normative perspective,” we focus on Scripture as instruction about God. In the “existential perspective,” we focus on ourselves and our subjective sense of consistency. In the “situational perspective,” we focus on the world around us, and observe its consistency. Consistency or logicality exists in all three. Since God is the source for all three, they are intrinsically in harmony–that is, apart from sin. Each of the three points to and in a sense encompasses the others, so there is no need for them to fight.

Sin leads to alienation from God, and in that alienation we are also alienated from his logicality. The Bible plays a key role in explaining the way of salvation in Christ. Through his salvation, God restores us to true knowledge of God. Then we grow in seeing God, the Bible, ourselves, and the world as we ought to. In this sense, it is important to “start with” the Bible, in order for it to serve the role that God has designed it to play in our thinking (Ps. 119:105). When we study the Bible, we are of course using reasoning abilities that God has given us. But since sin has corrupted our reasoning, sometimes in subtle, hidden ways, it is important that we be willing to submit our thinking to God’s instruction (2 Cor. 10:5).

At one point you state: “many people have thought that formalization and rigor in logic eliminate the need for God. Formal arguments appear to people to lead to conclusions in and of themselves, independent of any religious interference. Apparently, God is absent.” What is your response to that common line of reasoning?

If we carefully analyze our own ability to introduce formalization and rigor, we can see ways in which the process of formalization itself relies on complex rational, linguistic, personal abilities that have their roots in God and that rely on God. God’s Trinitarian character is reflected in the very structure of language and in the mini-transcendence that human beings exercise when they stand back to analyze logical operations and then formalize them. Formalization itself thus testifies to the wonder of God creating us in his image. Formalization depends on God rather than dispensing with him.

What is the Euthyphro dilemma and how has it posed a challenge to the way we relate God and logic?

In Plato’s dialogue Euthyphro, Socrates asks whether what is holy is “loved by the gods because it is holy,” or whether it is “holy because it is loved by the gods.” In context, the “gods” are the gods of Greek polytheism. Socrates and Euthyphro both agree that the first alternative is true.

We can of course translate this question into a monotheistic context. In this context, the first alternative leads to placing holiness above God. Then God is subject to holiness, which is an abstraction superior to him. The really ultimate absolute appears to be holiness rather than a personal God. Or if we choose the second alternative, holiness seems to be an arbitrary imposition, and not worthy of our allegiance.

Similar issues arise with respect to the status of logic. If logic is superior to God, then logic as an abstraction is the real absolute. On the other hand, if logic is what is specified by God, does that make it arbitrary? My answer would be that logic is an aspect of God’s character, related especially to the Logos, the second person of the Trinity. So we are not talking about an impersonal abstraction superior to God (as with the first alternative). And we are not talking about an arbitrary imposition of a “cooked up” logic (as with the second alternative), because logic expresses God’s character–his self-sufficiency. A biblical view of God enables us to go beyond the dilemma, by seeing the foundation for all thought in God. It also moves us beyond the dilemma by stressing the Creator-creature distinction. Our own knowledge of logic is derivative; God’s is original. We should submit to God’s voice, rather than making ourselves the ultimate standard for logic.

Can logic point us beyond the God of classic theism to the (Trinitarian) God of Scripture?

Yes. The Trinitarian character of God is fully revealed in the New Testament. Before the time of the fullest revelation in the New Testament, the Old Testament saints had hints and foreshadowings of the mystery of the Trinity, such as in the appearances of God in human form (Ezek. 1:26), foreshadowing the incarnation. But there was much mystery. It was always God in his Trinitarian character who was acting. But human knowledge of him was limited in Old Testament times. In the light of the fuller revelation in the New Testament, we can now see the reflection of his Trinitarian character in logic. Perhaps the easiest way to see this is by reflecting on the teaching about the Word of God in John 1:1. Logic is an aspect of God’s speech. And God’s speech involves a speaker (preeminently God the Father) and the speech (God the Son) and the Holy Spirit who is like the breath taking the speech to its destination. Logic is one aspect of this Trinitarian speech.

I am deeply sympathetic to your call to ground all knowledge on a thoroughly Christian basis. However, I wonder if specifically Christian premises could ever be the norm in the public square since not everyone can be assumed to possess a regenerate standpoint. Should an un-christian view of logic be tolerated (emphasizing common grace) or opposed (emphasizing the “antithesis”) in the academy, media, and public square?

You ask an excellent question, to which I do not think there is a simple answer. Wisdom is necessary in addressing each situation. I would emphasize that we who are Christians should realize that non-Christians as well are made in the image of God. Despite the corruptions of sin (to which we ourselves are still subject to some degree), non-Christians can never escape the presence of God. They are always relying on logic when they reason, and in doing so they are relying on God. But they are inconsistent, because they are in confusion: they rely on God, and simultaneously they tell themselves that they are relying on an abstract, impersonal principle.

At times, we might choose to make only a short-run argument, to help a non-Christian be persuaded of some proximate truth. We ourselves should always be relying on the rationality of God. And we are appealing to the non-Christian dialogue partner to do so too, but he continues to be confused about that on which he is relying. At other times, we may choose to bring up the deeper issues of principle–just what is it on which we are relying when we engage in reasoning? And that question leads to a discussion of the whole Christian worldview. It is indeed a whole worldview, and a non-Christian needs at some point to come to grips with just how radically different it is from that to which he is accustomed.

In sum, I believe that we should not “tolerate” a non-Christian logic in the sense of giving it our approval or saying that it makes no difference. But we should “tolerate”–better, show love to–the people who are in confusion, and try to lead them out of their confusion. In doing so, we will not “fit in” to non-Christian expectations about how people think, but we and they together live in God’s world. The message of the Bible comes to them not simply as truth, but truth tailored to lead them out of their darkness. The fundamental issues are always spiritual, not merely intellectual.

Back to Top