Logic Miniseries: Part 2 – Introduction to Logistical Terminology

Now that you’ve recovered from Part 1 (the laws of logic), it’s time to move on to Part 2.  For my attention grabber: what if I told you we’re going to be learning some logistical vocabulary in this post?  Good, you’re still here!  To make the vocabulary a bit more attractive, what if I also told you that I’ll be using examples from unbelievers?  Okay, I hope by now we have a deal.  Apologetics doesn’t have to be boring.  It’s all about presentation!  So let’s get started…

brain-770044_640Remember, logic is a reasonable or rational way of thinking about or understanding something.1  Although we take logic for granted because we’re not conscious of it all the time, we use it every day!  Now, whether or not we use it rationally every day, is debatable.  Okay let’s be honest; most of us are just plain awful at reasoning, sometimes.  Why?  Because most of us don’t know how logic actually works or what it means to be rational.

Let’s commence with our first vocabulary word – fallacy.  A fallacy is simply a common error in reasoning; there are tons of them (the common ones in apologetics will be addressed in later posts).  For example, “you either believe in science, or you believe in God.”  This is an example of the fallacy, bifurcation.  One commits this fallacy when presenting two propositions as if they were the only two options available, when clearly there could be a third.  So, when someone says, “you either believe in science or you believe in God,” politely let them know that as followers of Christ, we believe in both God and science.  The difference is, we look at science from a biblical worldview (putting God first – He created science), whereas unbelievers look at it from a secular worldview.  In other words, we both look at the same data, yet draw different conclusions based on our worldviews.

When someone presents a statement that can be assigned a truth value (true or false),question-738810_640 that’s called a proposition.  For example, “all humans have livers,” is a proposition and also happens to be true.  Here’s another, “all birds can fly,” is another proposition and also happens to be false.  When two or more propositions are given, where the truth claim of one follows another, that is called an argument.  So if I said, “(1) All humans have livers; (2) I’m human; (3) therefore, I have a liver,” that would be considered an argument.  Me having a liver is considered to be true because it follows the truth claims of the other two propositions.  Now, numbers (1) & (2) are also called premises, or propositions assumed to be true which support the conclusion.  Number (3) is called a conclusion; an asserted proposition based on the other propositions. In other words, the conclusion is the end of the propositional statement in which the truth claim follows from the other propositions.  Here’s another example, “(1) everything in the Bible is untrue; (2) creationism is taught from the Bible; (3) therefore, creationism is untrue.”  Although this serves as an argument, it’s an unreliable one.  Can you guess why?  The first premise is false (it’s also arbitrary, which I shall discuss shortly); therefore, the conclusion is unreliable.1

There are two basic systems of logic: deductive and inductive.  Deductive logic is a logical process in which a conclusion is based on the concordance of multiple premises that are generally assumed to be true.2  The arguments in the previous paragraph are examples of deductive reasoning.  In the previous paragraph with the premise, “(1) all humans have livers…,” this is an example of a valid argument.  Deductive arguments can either be valid or invalid depending on whether or not the conclusion actually follows the premises.  A deductive argument can also either be sound or unsound (invalid).  An argument is sound if the premises are true; if they are not, the argument is unsound/invalid.  “(1) Too many copies and translations for any literary work deems it untrustworthy; (2) the bible has been translated over 500 times and copied more than 5,600 times; (3) therefore, the bible is untrustworthy.”  This is an example of an unsound argument.  Why?  Premise (1) is not true.  The new testament alone is 99.5% accurate and the .5% inaccuracy is due mostly to sentence structure and punctuation.4

Inductive logic is a system of evidential support for something that is very likely to be true, and classified as ‘strong’ or ‘weak’ arguments.3  For example, “I came home and my wife wasn’t home, nor was our dog.  Therefore, my wife is probably walking the dog.”  This would be considered a strong argument, as the conclusion seems to support the premise.  However, with an inductive argument, information could be added which can alter the likelihood of the conclusion.  Let’s add another premise, “My wife rarely takes our dog for a walk,” (this isn’t really true, just using it as an example, lest my wife be reading this).  Because of the new information, the conclusion, “my wife is probably walking the dog,” is now less likely, or weak.

bible-896220_640We’re almost to the finish line!  If you’ve come this far, even if you’re a bit confused, great job!  Again, logic can make your head spin at times and normally requires multiple reads.  This last part will prove much easier on the brain and touches two simple vocabulary words (which you may have heard or read in an apologetic confrontation): arbitrary and conjecture.  Arbitrary statements look like this: “I’m moral and I don’t even believe in God,” “There is no such thing as God;” “Christians are idiots;” “One day, science will know everything.”  Arbitrary statements like these are subject to individual will or judgment without restriction.  In other words, they are contingent solely upon one’s discretion.5  Never let an opponent get away with statements like these.  Ask follow-up questions!  Arbitrariness usually gets tossed around when people are frustrated in conversation or debate on God.  It’s also the result of those who argue poorly.

Conjecture is somewhat similar to being arbitrary.  A conjectured statement looks like this, “God doesn’t exist because science has all but disproven Him.”  Here’s another: “God hasn’t revealed Himself to anyone; how can you believe that nonsense?”  So, the last two examples are formations or expressions of an opinion or theory without sufficient evidence or proof; thus, conjecture.6  The average unbeliever will usually start his defense with something arbitrary or throw out some conjecture.  These statements always need elaboration.  Again, ask follow up questions.  Ask a ton of them!  For example, in response to “I don’t need God in order to be moral;” ask, “How do you know you are moral?  What standard do you use for your morality?  How would you define morality?”  Then go from there.

See, that wasn’t so bad, was it?  If you said, “yes,” my apologies.  I tried making it as simple as possible.  Informal logic will probably be the most fun out of all the lessons, which I’ll be posting next.  I’ll go over common fallacies and also use a ton of real world examples from your average unbeliever.  I promise the next few posts will be much more enjoyable!



1  Lisle, J. 2009. The Ultimate Proof of Creation: Resolving the Origins Debate. Master Books: Green Forest, AR.

2  Rouse, M. (2013). Deductive Reasoning.  Retrieved from http://whatis.techtarget.com/definition/deductive-reasoning

3  Hawthorne, J. (2012). Inductive Logic. Retrieved from http://plato.stanford.edu/entries/logic-inductive/

4  Slick, M. (2016). Manuscript Evidence for Superior New Testament Reliability.  Retrieved from https://carm.org/manuscript-evidence

5  http://dictionary.reference.com/browse/arbitrary

6  http://dictionary.reference.com/browse/conjecture?s=t


Author:  Brian Kurkjian, Ed.D

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