Columbo’s Logic, Part 3

What? You don’t have these yet??

Today, we’re finishing up a look at how Greg Koukl’s “Columbo questions” in his book “Tactics” actually build on what’s called the 3 acts of the mind from classical logic. His first question, “What do you mean by that?”, sought to clarify the words being debated and results in understanding, the first act of the mind. His second question, “How did you come to that conclusion?”, sought reasons for why we should agree to a person’s statement. That is, appropriately enough, reasoning – the third act of the mind. But understanding what someone is saying and why they are saying it both have an end goal: being able to judge whether what they’ve said is actually true, and should be accepted. Getting at the truth is the objective of Greg’s insightful questions, and this requires the second act of the mind – judgment. So let’s jump in and work through that today.

“Judge not” seems to have become the two most popular words to take out of context in all of the Bible,  but judging things (and yes, people) is still necessary. In fact, it’s required for rational thought, for truth can only be discovered through judgment. Judgment is simply to decide on the truth or falsity of a statement. If I decide to drink from the jug of milk in the fridge that I forgot about a month ago, I have mistakenly judged the statement “It’s safe to drink chunky milk” to be true. That is a bad judgment, and one I’ll likely pay for. Knowingly hiring a child molester to babysit your kids would also be a case of very bad judgment. On the other hand, good judgment is valued enough that we even pay certain people to judge other people as their full-time job. We call them… judges. As an engineer, I am given a solemn responsibility to use my “professional judgment” to protect and safeguard the public for whom I’m designing something. But what constitutes good judgment and bad judgment?

Judgment is essentially the relation of two or more concepts to each other to make a statement about them that is either true or false. Judgment is propositional in nature, in that we cannot formulate judgments without forming declarative statements about what we’re judging. Just as in grammar, those statements (or propositions) have a subject about which we have something to say, and a predicate that predicates, or says something about, the subject. I’ve mentioned in parts 1 & 2 that terms and reasoning can’t be true or false, but only clear or unclear for terms, and valid or invalid for reasoning. But here, with propositions, we have a claim being made, and the possibility of it being true or false. We may not know whether the claim is true or false, but every proposition must be one or the other. “This apple is red,” “This chunky milk is OK to drink” “Hitler was a bad man,” “Jesus is God.” Each of those statements relates two concepts (like “apples” and “redness”) in such a way that we must decide if that relation is true or not. If I am holding a Granny Smith apple when I make that first statement, you would be justified in judging it a false proposition, for Granny Smiths are famously bright green rather than red. What warranted that judgment? Simply that my statement did not correspond with reality. While this may seem like common sense, this is technically known as the correspondence theory of truth, namely that truth is what corresponds to reality.  When we are presented with an assertion that we are trying to examine, judgment is needed to decide if the proposition asserted is true or not – if it corresponds with reality. A simple enough statement may be self-evident or immediately verifiable. But many topics, and especially controversial ones, will require hearing supporting statements that must also be judged as true or false.

Let’s look at an example of a modern hot topic. Abortion supporters will often say something to the effect of “my body, my choice” to say that women have a right to an abortion on demand. At that level, it’s only an assertion. But suppose a thoughtful supporter of abortion filled in the premises to that conclusion and said something like, “I have the freedom to do what I want to my own body. Abortion is a procedure done to my own body. Therefore, I am free to choose an abortion.” Although the reasoning is valid (i.e. the conclusion follows from the premises as stated), the second premise is obviously false; there are always 2 bodies involved in the procedure and the successful procedure always results in the death of one of them. If there’s any doubt that the baby is not part of the mother’s body, a simple DNA test can confirm that beyond all doubt. This one’s pretty straightforward since it’s a scientifically verifiable fact that the fetus is not part of the mother’s body. So the supporting premise is false and the original assertion can be dismissed, right? Not so fast. As Peter Kreeft points out in his logic text, “you do not refute a conclusion by showing that it follows from false premises.”[1] The thoughtful opponent could revise their premises to validly support their original conclusion, thus proving their case. So what have we accomplished in judging that premise false? We’ve shown that their case is not as airtight as they had probably assumed. It is inconclusive, and they need to go “back to the drawing board,” so to speak. Encourage them to revise it and get back with you. “Put a stone in their shoe”, as Greg likes to say.[2] Don’t be afraid of what they’ll come back with. If their conclusion really is false, then they simply will not be able to find true premises validly built up to support a false conclusion.

Most of us don’t like to admit we’re wrong about anything. And someone proving us wrong doesn’t make it an easier pill to swallow. So a lot of times, our approach needs to be to help someone see for themselves that their view doesn’t work, because they’re the only one they’ll really listen to. But I’m OK with that. Honest dialogue is like a long journey towards truth together rather than a quick and bloody duel of opinions that goes nowhere. But as ambassadors for Christ [2Cor 5:20], we have this advantage: “Regardless of a man’s system, he has to live in God’s world”[3], and a successful search for real truth, even if it meanders and hits some bumps along the way, will necessarily lead to God, for all truth is God’s truth.


[1] Peter Kreeft, Socratic Logic (South Bend: St. Augustine’s Press, 2010), p. 197.
[2] Gregory Koukl, Tactics: A Game Plan for Discussing Your Christian Convictions (Grand Rapids: Zondervan, 2009), p. 38.
[3] ibid, p144. Greg is quoting Francis Schaeffer here, from Schaeffer’s book, The God Who Is There.

Columbo’s Logic, Part 2

Recommended reading for clear thinking

Last week, we looked at Greg Koukl‘s classic book Tactics, and how his first “Columbo question”, “What do you mean by that?”, is an application of what’s called the first act of the mind in philosophy. This first act, understanding, is simply recognizing that we have to understand what we’re discussing before we can even hope to be able to decide if it’s true or not. His next critical question to ask is “How did you come to that conclusion?” While the first question addresses the what, this one addresses the why. This serves a couple of purposes: First, the person you’re talking to may have good reasons for holding the position they do, that you hadn’t thought of before, and this gives them the opportunity to share those. But secondly, it places the burden of proof where it belongs – on the person making the claim. As Greg points out, “an argument is different from an assertion… An assertion simply states a point. An argument gives supporting reasons why the point should be taken seriously….”[1] Yet many people haven’t thought through why they hold a certain position. Too often, it’s easier to sit in an echo chamber and not dialogue with people of opposing views who may challenge one’s views and legitimately ask for reasons for the claims made. But this question graciously gives your conversant the benefit of the doubt that they have thought about their position and actually have good reasons for why they hold their view. If they have, now’s their opportunity to convince you. If they haven’t, it can hopefully be a wake-up call for them to examine their beliefs. With that in mind, let’s think about the act of reasoning.

This “third act of the mind”, reasoning, is what allows humans to acquire  knowledge beyond our particular experience, and to abstract from particular truths to universal and/or necessary truths. Reasoning is also where we justify our claims by providing valid arguments. As I mentioned last week, the terms we use, by themselves, can be clear or unclear, but they can’t be true or false. Neither can our arguments; they can only be valid or invalid. What is validity? Peter Kreeft, in his Socratic Logic textbook, defines it thus: “An argument is logically valid when its conclusion necessarily follows from its premises.”[2] He further explains:

“Validity is a relationship between propositions: between the premises of an argument and the conclusion of the argument…. A valid argument gives us certainty about its conclusion. It is not absolute certainty but relative certainty, that is, certainty relative to the premises… certainty that if the premises are true, then the conclusion must be true.”[3]

Validity is the mechanical aspect of reasoning that allows us to know two specific relations between a conclusion and its supporting premises: when a conclusion must be accepted, and when a premise must be rejected. Let me explain. Sometimes, a case is being constructed in front of us, and we can follow the steps from defining the terms, to making statements about the terms, to “connecting the dots” with valid reasoning. In this case, a valid argument built on clearly-defined, true supporting premises will have a true conclusion. There is no other possibility given those three conditions. But oftentimes, we are simply presented with an assertion. This is the scenario Greg addresses with the Columbo tactic when he asks someone to clarify their terms and give their reasons that (hopefully) transform their assertion into a conclusion. He is working backwards, deconstructing the conclusion to check its foundation. And in this scenario, a valid argument with a conclusion known to be false guarantees that at least one of the premises is false. The validity of the reasoning isolates the problem to the premises. Kreeft likens this forwards or backwards reasoning process to following a river from its unpolluted source to its unpolluted conclusion downstream, or tracing pollution downstream back to its polluted source upstream.

These two acts, understanding and reason, are two necessary steps toward the end goal of truth. But truth is only conveyed in propositions, whether that be the supporting statements or the final conclusion. To judge the truth of those statements, we need to look next week at the 2nd act of the mind… judgement. Until then, here’s a little homework: next time you’re in a discussion with someone who holds a different view, politely try asking them for the reasons they hold that view. In the absence of any opportunities like that, examine the foundations for your own views. Are they sound? As Greg says, “Intelligent belief requires reasons”[1], and that is true for Christians, atheists – everyone.


[1] Gregory Koukl, Tactics: A Game Plan for Discussing Your Christian Convictions (Grand Rapids: Zondervan, 2009), p. 60.
[2] Peter Kreeft, Socratic Logic (South Bend: St. Augustine’s Press, 2010), p. 31.
[3] ibid., p. 194-5.

Columbo’s Logic, Part 1

The always inquisitive Detective Columbo.

2014 was a very busy year of reading for me. I’d applied to attend Frank Turek’s Cross-Examined Instructor’s Academy, and there was a veritable mountain of recommended reading to get through beforehand, both from noted Christian apologists and some of the most noteworthy atheist writers. That year was when I read a point-counterpoint debate on the existence of God for the first time. I was admittedly nervous about what points the atheist would make that might rock my world. As it turned out, I had little to fear (the atheist case really isn’t as strong as they like to pretend). But one of the books from that year that I have come back to time and again was Greg Koukl‘s book “Tactics: A Gameplan for Discussing Your Christian Convictions” (read a sample here). This is a classic book of critical reasoning that looks at concepts like self-refuting arguments, the burden of proof, and other basic principles of logic, explained well and with clear examples. One of the principal methods laid out in the book is what Greg calls the “Columbo tactic. Peter Falk’s classic bumbling detective character always ends up catching the bad guy by asking “just one more question”. The answers eventually reveal inconsistencies in the murderer’s alibi and the truth always comes to light. While we may not be hunting criminals, we are hunting for truth. And so Greg encourages a) asking questions of your fellow conversant, and b) actually listening to their responses. This is pretty radical in a world where people tend to talk (or shout) past each other, but isn’t that what actual dialogue should involve? The two primary questions Greg asks are “What do you mean by that?” and “How did you come to that conclusion?”[1] These are simple but very powerful questions because they first clarify what is being debated, and secondly seek to uncover their reasons (or lack thereof) for what they believe.  Although I recognized when I read Tactics that these were effective questions, it wasn’t until I read philosopher Peter Kreeft’s textbook on Socratic Logic in 2015 that I understood why.  Kreeft notes at the beginning of his logic text that “there is one simple, observable behavior that clearly distinguishes humans from both computers and animals: asking questions.”[2] Well, Greg doesn’t just ask any old questions, but rather two insightful questions built on the tried and true foundation of classical logic. These directly address the “three acts of the mind”: understanding, judgement, and reason. Let’s look at each one closer over the next few weeks, starting with understanding.

Understanding, traditionally called the first act of the mind, is what Kreeft says most clearly distinguishes humans from computers: “computers understand nothing; they merely store, process, relate, and regurgitate data.” [3] While judgement and reasoning deal in propositions and arguments, respectively, understanding starts with the foundational level of terms. Terms can’t be true or false by themselves, but they can be clear or unclear. There are often multiple words that might be applicable in a particular situation, and most words have multiple meanings depending on the context. Not defining terms is the most frequent cause of people talking past each other. This is typically unintentional, as each person may simply have a different concept in mind when they hear a certain term. Defining a contentious term in a discussion locks down the word used to the actual concept intended and gets both parties “on the same page”, so to speak. This is especially important with controversial topics that can have a lot of connotations beyond the basic definition. A person may also start out using a word one way and switch mid-discussion to a different meaning. Whether intentional or not, this is actually a logical fallacy called equivocation, and is often used to seemingly prove a point – until we examine the change in meaning midstream. Asking your friend “What do you mean by that?” can help highlight (for both of you) when a word is used inconsistently.

To see how definition helps both parties in a conversation to understand each other better, take, for instance, the controversial topic of abortion. Suppose Susan makes the statement “Abortion is wrong” in a conversation with Beth. If Beth takes “wrong” to mean “illegal”, then she will likely disagree with this premise; it’s not currently illegal (here in America). They might go back and forth and get nowhere because Susan defines the term “wrong” as immoral, while Beth defines it as illegal. But of course, not everything that is wrong is illegal (i.e. killing Jews in Nazi Germany was legal, and even rewarded), while not everything that is illegal is wrong (i.e. owning a Bible in North Korea can get you sentenced to a slave labor camp or executed).

Greg’s advice to ask “What do you mean by that?” early on helps avoid the embarrassing admission after the fact of “we got in a big fight and it turned out we weren’t even talking about the same thing…” On that note, this week’s post comes with some homework: 1) look for opportunities this week to try verifying what people mean (hopefully before getting in a fight!), and 2) think about the words you might be using carelessly, and how clearer terms may help better your own understanding of issues, as well as for people with whom you’re communicating.

Next week, we’ll look at Greg’s second question and how it builds on the third act of the mind, reasoning. Then we’ll circle back to the second act of the mind, judgment, to put everything together.


[1] Gregory Koukl, Tactics: A Game Plan for Discussing Your Christian Convictions (Grand Rapids: Zondervan, 2009), p.49,61.
[2] Peter Kreeft, Socratic Logic (South Bend: St. Augustine’s Press, 2010), p. 35.
[3] ibid. p.36.