Weekend Broadcast

Four Steps Backwards

A Message by R.C. Sproul

Many atheists have tried to disprove the existence of God by attacking four basic assumptions about reality. These assumptions are: The law of non-contradiction, the law of causality, the principle of the basic reliability of sense perception, and the analogical use of language. In this lesson, Dr. R.C. Sproul introduces these concepts and explains why they are essential to defending our faith.

From the series: Defending Your Faith

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Further Study On This Topic

  1. devotional

    Law of Noncontradiction

  2. article

    Logical Fallacies

  3. article

    All Truth Is God’s Truth

Law of Noncontradiction

Unfortunately, many modern Christians do not consider the mind to be all that important in the Christian life. This is largely due to the fact that many academics in the church have betrayed orthodoxy and have used their minds to mount an assault on Christian belief. In seeking to preserve the truth, many evangelicals have sought to accept Christian doctrine solely on faith. This is not necessarily unacceptable, except that they have defined faith as being incompatible with reason.

Faith and reason, however, belong together. Apart from faith, reason leads to futility. Without reason, faith becomes a blind leap that embraces contradictions. We see how this happens when people accept contradictory interpretations of Scripture as being equally true.

But God cannot contradict Himself. If He did, we could not believe what He says or know how to follow Him. If two people give a contradictory understanding of a text, either one of them is wrong or both of them are wrong. Both, however, cannot be right. Otherwise, the concept of truth loses all meaning.

God’s judgment on disobedience proves the point. God punished Adam and Eve for eating what He told them not to eat. If contradiction and truth were compatible, God could not have condemned Adam. How could God find them guilty if His prohibition against eating the fruit really could mean “do not eat the fruit” and “you may eat the fruit” at the same time and in the same sense?

God’s judgment on disobedience demonstrates that the Bible assumes the existence of one of the fundamental laws of reason, the law of noncontradiction. This law states that “A cannot be both A and non-A at the same time and in the same relationship.” In this proposition, “A” refers to an object being discussed. For example, “A” could be grasshoppers. “Non-A” refers to any other object that is not “A.” For the purpose of our example, “non-A” could be whales, tables, cars, bluebirds; anything except grasshoppers. Thus we arrive at the proposition: Grasshoppers cannot be both grasshoppers and whales (not grasshoppers) at the same time and in the same relationship.

The law of noncontradiction is vital to the intelligibility of faith and life. Without it, the concept of truth loses all meaning. Tomorrow we will explore the law further and see its use in life and theology.

Logical Fallacies

Andreas Kostenberger

Logic (from the Greek word logos, "reason") is the "science that deals with the principles and criteria of validity of inference and demonstration, the science of the formal principles of reasoning" (Merriam-Webster). While theology, as the study of God, transcends mere logic, it is reasonable to expect that Scripture adheres to common principles of reasoning. Properly used, logic derives true propositions from other true propositions. Even though Scripture may not explicitly state a given truth, we may make true statements that have Scripture's authority behind them if they are properly derived from what Scripture does say following principles of logical reasoning.

A basic understanding of the rules of logic is crucial to sound hermeneutics. Logical fallacies, both formal and informal, are found in every field of study, and biblical exegesis is no exception. In what follows, I will provide examples of some of the most common logical fallacies encountered in biblical studies. They are: (1) false disjunctions, (2) appeals to selective evidence, (3) unwarranted associative jumps, (4) improperly handled syllogisms, (5) false statements, and (6) non sequiturs.

False disjunctions are made when an argument is presented in an either or fashion: either A or B is true, but not both. However, there are times when the answer is "both/and" rather than "either/or." Take the relationship between Galatians 3:28 and 1 Timothy 2:12, for example. It is at times claimed that Paul's assertion in Galatians 3 that in Christ there is "no male and female" eradicates all gender-related distinctions with regard to church ministry, so that the prohibition of women teaching or exercising authority over men in the church in 1 Timothy 2 must be explained as a culturally relative injunction. Both— undifferentiated male-female equality in Christ and limiting authoritative local church offices to men—cannot be true, it is said (or at least implied), so the latter principle must be relativized in such a way that it fits with the former. However, this kind of disjunctive thinking is fallacious. Since 1 Timothy 2:12 is grounded in creation's design and, conversely, the scenario at the fall (vv. 13–14), the passage cannot easily be set aside as culturally bound. More promising is the explanation that Galatians 3:28, in affirming the irrelevance of male-female distinctions with regard to salvation in Christ, is not seeking to address male-female roles in the church at all, so that the passages are pertaining to different (albeit related) topics. Both affirmations are true: men and women are indiscriminately saved by grace through faith in Christ, and the office of elder/overseer is reserved in Scripture for men in keeping with God's creation design.

Appeals to selective evidence are numerous. By definition, we engage in this logical fallacy anytime we only refer to authorities or passages that agree with us on a given issue while failing to account for countervailing evidence or authorities. A specific example comes from the "name it and claim it" theology. In circles that embrace this sort of thinking, it is common to cite Scripture passages that promise answers to prayer for "whatever you ask." For example, in John 14:13–14 Jesus says: "Whatever you ask in my name, this I will do, that the Father may be glorified in the Son. If you ask me anything in my name, I will do it." At other times, Scripture stresses the need for faith on the part of the one who prays (Heb. 11:6; James 1:6). However, people can sustain the name-it-and-claim- it approach only by selective use of evidence while ignoring other passages that put certain constraints on the kinds of prayers God will answer: prayers of disciples who take up their cross and follow Jesus, prayers asking for resources to carry out God's mission in the world, and so on. Such proponents also tend to ignore the mystery of suffering (see, for example, Jesus' comments in Luke 13:1–6), fail to explain why God answers certain prayers but not others (such as for the salvation of loved ones), and neglect to point out that there is no scriptural guarantee that God will answer all prayers for healing.

Unwarranted associative jumps, likewise, are treacherous and lurk at every turn. D.A. Carson, in his excellent book Exegetical Fallacies, cites the classic example of Paul's statement in Philippians 4:13, "I can do all things through him who strengthens me." All things? As Carson rightly points out, Paul's statement cannot be legitimately extended to such things as jumping over the moon, integrating complex mathematical equations in one's head, or turning sand into gold.

Certain constraints are brought to bear by the context of Paul's statement in his letter to the Philippians, most importantly the importance of contentment and of being able to deal with both poverty and wealth. Another common example of an associative jump is taking 2 Chronicles 7:14 ("If my people who are called by my name humble themselves . . . ") as directly applying to modern-day democracies when the original point of reference was to Israel as a theocracy.

Improperly handled syllogisms are very common as well. An example of a two-step argument for women serving authoritatively in the church based on the application of the term co-worker (Greek synergos) to both Timothy (Rom. 16:21) and women such as Euodia and Syntyche (Phil. 4:2–3) might look as follows:

Syllogism No. 1:

  1. Timothy is a co-worker of Paul.
  2. Timothy functioned authoritatively in the church.
  3. Therefore, all co-workers of Paul functioned authoritatively in the church.

Syllogism No. 2:

  1. Euodia and Syntyche are co-workers of Paul.
  2. All co-workers of Paul functioned authoritatively in the church (the conclusion of the first syllogism).
  3. Therefore, Euodia and Syntyche functioned authoritatively in the church.

However, there are several problems with this kind of reasoning. Most importantly, the first syllogism is invalid: the conclusion does not properly follow from the premises. That is, if one were to say (1) some A is B and (2) all B is C, then one cannot from these premises categorically conclude that (3) all A is C.

At best, one could seek to work inductively and contend that there is a strong likelihood that all co-workers of Paul functioned (or could function) authoritatively in the church. However, this would be a difficult case to prove, because contextual study of the relevant passages suggests that co-worker in the New Testament is a more flexible term that may indicate various forms of partnership, whether joint ministry, financial support, or other ways of collaboration. In any case, our point here is that arguments based on syllogisms, while common and often having surface appeal, may turn out at closer scrutiny to be fallacious and unsustainable.

False statements are also quite common, though perhaps this category would better be labeled "the use of faulty premises." This fallacy may also be related to the just-mentioned faulty use of syllogisms. Remember, even if a syllogism is formally valid, as we have seen, the conclusion may still be false if one or both of the premises are faulty. An example of this is the common manner of citing Proverbs 29:18: "Where there is no vision, the people perish," with vision being used to indicate a leader's or group's forward-looking plans, desires, and expectations instead of the prophetic revelation that seems to be in view here. This is wisely brought out by the ESV translation of the verse: "Where there is no prophetic vision the people cast off restraint" (emphasis added).

While I could continue, I'll close with one of my favorite categories, that of non sequiturs (Latin for "does not [logically] follow"). Many examples could be given, but perhaps most common under this rubric are illegitimate arguments from silence. For example, consider the not-uncommon assertion that the reason why Mark and John don't mention the virgin birth is that they either didn't know about it or, if they did, didn't believe in it. This clearly doesn't follow logically and is both a non sequitur and an illegitimate argument from silence. What about other reasons, such as Mark's desire for concision or John's reference to Jesus' eternal preexistence as the Son of God?

Even more importantly, I'd love to have a nickel for every time I've heard the argument that because Jesus never explicitly addressed the subject of homosexuality, we can safely surmise that He condoned such a practice. This assertion, of course, overlooks the fact that Jesus unequivocally stated, "Have you not read that he who created them [the man and the woman] from the beginning made them male and female, and said, 'Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh?'" (Matt. 19:4–5). It is hard to infer from this strong affirmation of heterosexual marriage that Jesus condoned same-sex marriage.

These examples highlight the importance of engaging in proper logical reasoning when interpreting Scripture. I don't have space to address numerous other fallacies here, such as those related to emotive appeals, cavalier dismissals, improper analogies, simplistic appeals to authority, fallacies based on equivocal argumentation, and the improper use of obviously and similar expressions. Suffice it to say that every worker who truly desires God's approval in his handling of Scripture (2 Tim. 2:15) will do well to apply himself earnestly to sound principles of logic and proper reasoning.

All Truth Is God’s Truth

R.C. Sproul

Few books I have read have made a lasting impression on my mind and thought. One of them I read over fifty years ago. The title of the book was The Metaphysical Foundations of Modern Science, and it made a lasting impression upon me because it clearly set forth the importance of understanding that all scientific theories presuppose certain philosophical premises. The philosophical premises that are the underpinning of scientific inquiry are often taken for granted and never given even a cursory exploration. But in a time when fierce debate rages between science and theology, it is important that we step back and ask questions about the pre-scientific theoretical foundations for the whole enterprise of knowledge.

The word science means “knowledge.” We tend to have a restricted view of the word as if knowledge only applies to the realm of empirical investigation. Besides material knowledge, we also have to take into account formal truth. In this regard we must consider mathematics as a genuine science, because math in its formal dimension yields real knowledge. In fact, if we look at the history of scientific progress, we see that the engine that has driven new breakthroughs and brought to bear new paradigms has more often than not been the engine of formal mathematics. But it is astonishing to see how frequently people engaged in material scientific research glibly pass over the philosophical presuppositions of their own work.

In Carl Sagan’s famous book entitled Cosmos, based on his television series of the same title, he makes the following statement: “Cosmos is a Greek word for the order of the universe. It is, in a way, the opposite of chaos. It implies the deep interconnectedness of all things.” In this seemingly harmless definition of the entire structure of Sagan’s work, he assumes that the universe under investigation by science is a cosmos rather than a chaos. He speaks of cosmos “implying a deep interconnectedness of all things.” This is the grand presupposition of scientific inquiry, namely, that the universe we are seeking to know is coherent. There is an implied deep and profound interconnectedness of all things. The alternative to cosmos, as Sagan has indicated, is chaos. If the universe is at root chaotic, then the whole scientific enterprise collapses. If the universe is chaotic and disconnected, then no knowledge is possible at all. Even discreet bits of atomic data cannot be understood within the framework of utter chaos, so the presupposition of a coherent, rational order of all things is the screaming presupposition of scientists.

This idea of an assumed coherency has its roots in ancient philosophical inquiry. Ancient Greeks, for example, sought ultimate reality. They sought a foundational principle for unity that would make sense out of diversity. This ultimate unity is what the science of theology provides. The science of theology provides the necessary presupposition for modern science. This is precisely the point that led prominent philosopher Antony Flew to his conversion from atheism to deism — namely, the essential necessity of a coherent foundation to reality to make any knowledge possible. This ultimate coherency cannot be provided by the contingency of this world. It requires a transcendent order.

In the Middle Ages, a crisis ensued in the realm of philosophy with the revival of what Muslim thinkers called “integral Aristotelianism.” In their attempt to achieve a synthesis between Aristotelian philosophy and Muslim theology, these thinkers produced a concept called the “double-truth theory.” The double-truth theory argued that what was true in religion could be false in science, and what was true in science could at the same time be false in religion. To translate that into contemporary categories, it would go something like this: As a Christian, one could believe that the universe came into being through the purposive act of a divine Creator while at the same time believing that the universe emerged gratuitously as a cosmic accident. These two truths examined by logic would appear to be contradictory. Nevertheless, the double-truth theory would say that truth is contradictory, and one could hold these contradictory ideas at the same time. This kind of intellectual schizophrenia rules the day in our own time where people think that God had nothing to do with the formation of the cosmos from Monday to Saturday only to become creationists on Sunday, failing to see that the two concepts are utterly irreconcilable.

At this point, the question is raised, “Well, does logic really count in our attempt to understand reality?” Again, if we’re going to assume coherency and cosmos, logic has to count not just for something but for everything. Thomas Aquinas responded to the Aristotelianism of the medieval Muslim philosophers by replacing double truths with the concept of mixed articles, distinguishing nature and grace (not dividing them, as many of his critics allege). Aquinas said that there are certain truths that can be known through special revelation that are not discerned from investigation of the natural world, while at the same time there are certain truths learned from the study of nature that are not found, for example, in the Bible. One does not find the circulatory system of the human body clearly set forth in Scripture. What Aquinas was saying was that there are certain truths that are mixed articles, truths that can be known either from the Bible or by a study of nature. Among those mixed articles, he included the knowledge of the existence of a Creator.

The fundamental point, of course, that Aquinas was arguing, in agreement with his famous predecessor, Augustine, was that all truth is God’s truth, and that all truth meets at the top. If science contradicts religion, or if religion contradicts science, at least one of them must be wrong. There have been times in history where the scientific community has corrected not the Bible but poor interpretations of the Bible, as we saw in the Galileo scandal. On the other hand, biblical revelation can act as intellectual brakes upon scientific theories that are groundless. In any case, if knowledge is possible, what Sagan assumed must continue to be assumed — namely, that for truth to be known, for science to be possible, there must be a coherent reality that we are seeking to know.

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