"Understanding is the reward of faith. Therefore seek not to understand that you may believe, but believe that you may understand."- St. Augustine of Hippo
"Understanding is the reward of faith. Therefore seek not to understand that you may believe, but believe that you may understand."
William Lane Craig's audio commentary on current events from his Defenders class. Various short commentary bits every week. The most recent, commentary on an article called: Why are atheists so boring?
Today we will look at logical fallacies. A fallacy is simply an error in thinking. Certain errors are so common they have been classified and named. These are the sorts of fallacies we are dealing with here.
In the study of logic, language plays a key role. Clarity in language is essential in order to communicate accurate meaning. The goal when looking at language is to determine the intent of the communication. Determining the intent or goal of your communication and understanding the intent of the one you are communicating with is the crucial first step in gaining clarity.
Logical thinking is a process. As long as the rules are not broken, the thought process will bring good conclusions. Now we will look at logical syllogisms.1. All cats are mammals.The categorical syllogism has various forms and moods, which will not be detailed here, but the basic form simply entails two statements leading to a conclusion.
2. Fuzzy is a cat.
3. Therefore, Fuzzy is a mammal.
If P, then Q.Modus ponens means “way of affirmation” in Latin because it affirms the antecedent of the first proposition. One form of the cosmological argument takes the form of modus ponens:
P.
Therefore, Q.
If a contingent being exists, then a necessary being must exist as its cause.The other hypothetical syllogism is called Modus Tollens, which means “the way of denial.” This form of syllogism denies the consequent (the “then Q” part of the first statement). It is structured like this:
A contingent being exists.
Therefore, a necessary being must exist as its cause.2
If P, then Q.Disjunctive Syllogisms are either/or sentences. One statement is made with two alternatives, of which only one can be true.3 The disjunctive syllogism looks like this:
Not Q.
Therefore, Not P.
Either P or Q.The way the disjunctive syllogism works requires for one alternate to be denied for the other one to be true. It is a fallacy to affirm one alternate to eliminate the other, because it is possible for them both to be true. Geisler and Brooks offer an excellent example of this fallacy found in Bertrand Russell’s book Why I am not a Christian:
Not Q.
Therefore, P.
Life was caused either by evolution or by design.Geisler and Brooks explain: “This approach commits the formal fallacy of affirming one alternate. Even if the minor premise were true, the conclusion would not follow. For it is possible that both are true; that is, that evolution is designed.”4
Life was caused by evolution.
Therefore, it was not caused by design (so there is no reason to posit God).
Both P and Q are true.The conjunctive syllogism is fairly straightforward. Both terms in the first statement are separated and can be affirmed individually.
Therefore, P.
Therefore, Q.
(If P, then Q) and (If R, then S).The mathematician Pascal presented a dilemma with this syllogism:
P or R.
Therefore, Q or S.
If God exists, I have everything to gain by believing in him.The final syllogism presented here is the Sorites. This comes from a Greek word meaning “heap.” The premises are stacked together in a heap to come to a final conclusion. An example:
And if God does not exist, I have nothing to lose by believing in him.
Either God does exist or he does not exist.
Therefore, I have everything to gain or nothing to lose by believing in God.5
All A are B...............or...............If A then BThat is a basic look at basic logical syllogisms.
All B are C...............or...............If B then C
All C are D...............or...............If C then D
Therefore, all A are D......or.....Therefore, if A then D.
Now we will discuss some of the basic building blocks in the study of logic. In general, everything else is built upon these essentials.Many passages, both written and spoken, that appear to be arguments are in fact not arguments but explanations. The occurrence of certain premise- or conclusion-indicators such as “because,” “for,” and “therefore” cannot settle the matter, since those words may be used in both explanations and arguments. What we need to know the intention of the author of the passage.3So the careful thinker must discern the difference between explanations and arguments by looking closely at context and intention.
A deductive argument is one whose conclusion is claimed to follow from its premises with absolute necessity, this necessity not being a matter of degree and not depending in any way on whatever else may be the case. In sharp contrast, an inductive argument is one whose conclusion is claimed to follow from its premises only with probability, this probability being a matter of degree and dependent upon what else may be the case.4One way to look at this is as follows: in a deductive argument, no amount of additional information can change the conclusion of the argument. In an inductive argument, the conclusion may change when new information is discovered. Deductive arguments are certain, whereas inductive arguments are probable to some degree.
Logic studies the methods that we use to analyze information and draw valid conclusions. As Norman Geisler and Ronald Brooks put it, “Logic really means putting your thoughts in order.”1 They offer their formal definition: “Logic is the study of right reason or valid inferences and the attending fallacies, formal and informal.”2 Their simplified definition: “Logic is a way to think so that we can come to correct conclusions by understanding implications and the mistakes people often make in thinking.”3
"Man, made in the image of God, has a purpose - to be in relationship to God, who is there. Man forgets his purpose and thus he forgets who he is and what life means."
During the coming week we will be featuring a series of 5 posts on the topic of logic. The purpose of this series of posts is to introduce the reader to the basics of logic. This is by no means a complete survey of the subject of logic, but is intended to serve as a very basic primer. This series of posts will consist of the following:
Informal Logic: A Pragmatic Approach (2nd Edition) by Douglas Walton is a logic book that offers the student an understanding of practical logic in dialogue and a deeper grasp of the common logical fallacies.
Craig Parton, American director of the International Academy of Apologetics, presents a talk on the topic: Whatever Happened to Apologetics? A good introductory lecture on apologetics. More Craig Parton resources can be found at truthincontext.org.
Philosopher Paul Copan discusses some of the issues in his book That's Just Your Interpretation. (book here) Original audio interview on Faith and Family.
Professor of New Testament interpretation Bill Cook presents a lecture on the topic: Trusting the New Testament. This talk takes a look at the Gospels and compares the historical accounts, writing styles, intent of the authors, and literary devices used throughout. Found here, where you can find more NT reliability audio.
Logic by Gordon Clark is a short (135 pages) introductory text on logic. Clark, a Calvinist theologian and philosopher, writes a more philosophical introduction to logic, many times from his distinct Christian perspective. He writes in a style that is almost conversational, from teacher to student.
"To have a right to do a thing is not at all the same as to be right in doing it."
Nonsense: A Handbook of Logical Fallacies by Robert Gula is a wonderful book which is both loaded with high quality content and easy to read. Falling into the categories of logic, critical thinking, and communication, this book is very useful to cutting to the core of the issue at hand and finding truth.When an argument is unsuccessful, it has probably gone wrong in one of the following areas: 1) The evidence has not been thorough; contradictory evidence has been overlooked or ignored; 2) The evidence has not been accurate; false or unsubstantiated or misleading statements have been claimed as fact; 3) The conclusion has not clearly and uncontrovertibly come form the evidence; the relationship between evidence and conclusion has not been a firm one.1The most common categories of informal fallacies are those of irrelevance, confusion, and oversimplification. The author spends time focusing on each one of these categories, splitting them into smaller subcategories as he goes along. Within this book he lists some 170 fallacies (not an official list), with many falling into multiple categories.
Dan Brown has released his latest book-to-movie: Angels and Demons. Today's featured web site is The Truth About Angels And Demons.com, which seeks to present a balanced assessment of Dan Brown’s narratives, the historical data, and the philosophy set forth in his best-selling novels and movies.
Philosopher Bruce Little speaks on the topic: God and the existence of evil and suffering. Bruce Little's theodicy book is here.
William Lane Craig presents a talk on the challenge of evil and suffering entitled: How Can a Good God Allow Suffering and Evil? This talk is followed by about an hour of Q&A. The text outline of this talk can be found here, and the original audio can be found here.
Dr. Hugh Ross and Dr. Walter Kaiser (representing old Earth creationists) debate Mr. Ken Ham and Dr. Jason Lisle (representing young Earth creationists) and present their views about whether the creation days were 24-hours long or long periods of time, what is the age of the universe and the earth, the relationship of the Bible and science, and more.
"The interval then between the date of original composition and the earliest extant evidence become so small to be in fact negligible, and the last foundation for any doubt that the Scripture have come down to us substantially as they were written has now been removed. Both the authenticity and the general integrity of the books of the New Testament may be regarded as finally established."
Being Logical: A Guide to Good Thinking by D. Q. McInerny is an excellent choice for an introduction to logic. There are a number of reasons why this makes a great first text. First, it is written plainly. The student is introduced to logical ideas without being bogged down by jargon or cumbersome technical language. Second, the ideas flow smoothly and naturally from the basic to the complex. The ascent is steady and gradual and it just makes sense; it doesn’t “drop” the reader when introducing new concepts. Third, its small size (160 pages) is just right for an introductory text. It is a very manageable, light, and readable text.
The notable apologist Francis Schaeffer has had a great impact upon 20th Century apologetics. His books continue to be a great influence. Now learn more about the life and thought of Schaeffer in this series of lectures by Dr. Kim Riddlebarger (originally found here).
Christian apologist John Warwick Montgomery has a number of good audio resources available, found here and here.
The Truthbomb Apologetics blog has been featuring an ongoing series of apologist profiles from such Christian apologists as William Lane Craig, J.P. Moreland, Ravi Zacharias, Paul Copan, Gary Habermas, Norman Geisler, Ron Rhodes, and Greg Koukl. Each profile provides articles, media, and links to other resources by each apologist.
Kenneth Samples is an apologist with Reasons to Believe. He is author of numerous books, including: World of Difference, A: Putting Christian Truth-Claims to the Worldview Test and Without a Doubt: Answering the 20 Toughest Faith Questions. The lectures below were found here.
Come Let Us Reason: An Introduction to Logical Thinking by Norman Geisler and Ronald Brooks is a useful introduction to logic written with the Christian in mind. This sets the text apart in the area of the examples used and some of the commentary involved throughout each chapter. This does not change the content of the logic being taught, but it does add another dimension to the book. We are exhorted, “The next best thing besides godliness for a Christian is logic.”1
"My belief has come about in large measure because of the lives and examples of people I have known - not the famous, not saints, but friends and relations who have lived, and faced death, in the light of the Resurrection story, or in the quiet acceptance that they have a future after they die."
Introduction to Logic (11th Edition) by Irving M. Copi and Carl Cohen is a standard textbook that gives a broad and fairly thorough introduction and overview of logic. The book is designed with the student in mind with numerous exercises in each section and a companion website at www.prenhall.com/copi.
Albert Mohler is president of Southern Baptist Theological Seminary and his radio show is a daily cultural commentary from a Christian perspective, covering a wide variety of current topics. His blog can be found here. Subscribe to the podcast in iTunes.