Asking someone what logic is in a conversation will no doubt draw blank stares of confusion and bewilderment. To many people logic is the stuff mathematicians and philosophers discuss and has no relevance for the man on the street. But this could not be further from the truth. Logic pervades our everyday lives through our thought processes and accompanying speech. And contrary to a secular and naturalistic understanding, logic does not exist independently on its own but is rather rooted in the nature and character of God.
With the goal of presenting a Christian view of logic, Vern Poythress has written Logic: A God-Centered Approach to the Foundation of Western Thought. The book is written in two parts. The first part addresses Christian foundations for understanding logic and the second part provides an introduction to logic itself. There is a sense in which this is two books in one. Peppered throughout the second part are introductory chapters in which Poythress returns again to the argument of the first section in order to establish a God-centered understanding of logic and explore the theistic foundations of logical functions, quantification, computation and the like.
A Christian perspective
While Logic can be used as an introductory textbook on logic, Poythress has written the book from an unapologetically Christian perspective. We can either view logic autonomously or as Christians. Since we are to hold every thought captive to Christ, we must ask ourselves if “allegiance to Christ actually makes a difference in logic” (p. 40). Poythress argues that it does. To go a step further, he, not surprisingly, defends the Christian nature of logic from a presuppositionalist perspective. We all have pre-commitments about our view of the world, and the Christian has specific presuppositions regarding God and His word. A Christian is to view logic through these presuppositions. We are to submit our thoughts, and our thoughts about logic, to the knowledge of Jesus Christ.
If logic does not exist on its own in neutrality, then what forms the foundations for its existence? The triune God. First, Poythress argues that logic reveals the character of God (chap. 7). Logic is consistent, dependable and universal in its application to all people everywhere for all time, and its laws possess a mystery to them. The characteristics of logic can only work when we begin with the character of God. Second, logic is personal rather than impersonal (ch. 8). Logic is inherently rational and rationality is an attribute of persons. “In practice all human beings believe that logic expresses rationality. This rationality in logic is accessible to human beings. But, as we know, rationality belongs to persons, not to rocks, trees, and subpersonal creatures. If the logic is rational, which we assume it is, then it is personal” (p. 68).
In turn, logic functions and is expressed through language. “Laws of logic are clearly like human utterance in their ability to be grammatically articulated, paraphrased, translated, and illustrated. Language, like rationality, belongs to persons. It follows that logic is in essence personal” (p. 68-69). He states further, “They are in fact personal; they are the expression of the language of God and the self-consistency of God, which is in harmony with the personal love of the Father for the Son and the Son for the Father, through the Holy Spirit” (p. 173). Third, logic is rooted in the trinitarian nature of God as Father, Son and Spirit. Logic is inherently linguistic, and language comes from God as the original speaker. Poythress writes, “Within God’s original divine speaking, the meaning of his speech has a correlation with the plan of God the Father; the ‘grammar’ has a correlation with the Word; and the speech has specific form through the Holy Spirit as the divine breath” (p. 76). For those who are still unconvinced, Poythress points to how the unity and diversity of God undergirds logic.
God is one. He has a unified plan for the world. The universality of logic reflects this unity. God is also three persons, the Father, the Son, and the Holy Spirit. This diversity in the being of God is then reflected in the diversity in the created world. The many instances to which logic applies express this diversity. Moreover, unity and diversity are expressed anther way. The unity of God’s plan has a close relation to the Father, the first person of the Trinity, who is the origin of the plan. The Son, in becoming incarnate, expresses the particularity of manifestation in time and space … Thus he is analogous in his incarnation to the fact that one universal logic expresses itself in particular instances. (p. 87)
When all is said, logic depends on God. When we examine the characteristics of logic, such as rationality and language, we must conclude that it is grounded in God who is the source of both. If it were separate from God, it would be in competition with God and possibly over God. This is not a Christian way to think of logic.
A fallen view of logic
If logic is necessarily dependent upon God, how do people not recognize this and instead develop godless views of logic? True to his theological commitments, Poythress points to the far reaching effects of the Fall on the thoughts of man. It is a matter of the heart’s disposition towards God Himself. Scripture teaches us that man is in open rebellion against God (Ps. 2, Rom. 1). In sin, mankind suppresses the truth of God because his heart is darkened. Man substitutes the creation for Creator. “This process of substitution takes place in the case of logic as well as in other areas. We engage in substituting an impersonal conception of logic for the reality of its personal character. This substitution is a form of idolatry” (p. 81). Because logic reveals God to us, man suppresses this truth in an effort to remove God from the picture. Man can know true things about logic, such as its rules, but he does so despite rejecting its only possible foundation and source—God Himself. The thoughts of the unregenerate mind on logic need to be redeemed. As the subtitle of the book indicates, we need an uprooting of the Western view of logic that has pervaded our history.
If our thinking about reasoning needs redeeming, we are not going to be able confidently to use reasoning in the way it has often been understood in the Western tradition. We must have a more reliable foundation. God himself is that foundation. We come to know God through Christ. God instructs about his ways in the Bible. By loving him and absorbing his instruction, we have hope of coming to a sound understanding of reasoning and logic. (p. 37)
In short, what man suppresses from the God-centered view of logic is His display of “his eternity, omnipotence, omnipresence, immutability, transcendence, immanence, and truthfulness in the laws of logic” (p. 517).
There is much more that can be drawn from Poythress about the relationship between God and logic. One of the shining chapters of the book is chapter 24 in which Poythress examines the traditional five theistic proofs for the existence of God. Even here, Poythress argues, one’s pre-commitments concerning the existence of God play a role in the ability to convince the unregenerate mind that is darkened by its heart of sin and rebellion towards God.
In typical Poythress fashion, the chapters are short, and most of them are easy to handle. Even with a topic such as logic, Poythress does a masterful job of explaining its trinitarian foundations and the many forms in which logic manifests itself. The book is biblical and consistent in its approach to the subject.
As a textbook on logic, this book is like many others. As a book on logic that is self-consciously written from a Christian perspective, the book provides the Christian with the theological, philosophical, epistemological and ontological foundations for logic that are submissive the lordship of Jesus Christ in all things to the glory of God. Not all Christians will be convinced of Poythress’ argument but it needs to be given serious consideration.
About the author
Vern S. Poythress is professor of New Testament interpretation at Westminster Theological Seminary, where he has taught for 33 years. He has six earned degrees, including a PhD from Harvard University and a ThD from the University of Stellenbosch. He is the author of numerous books on biblical interpretation, language, and science.
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