Everybody thinks everyday. There are no exceptions. But just because someone is thinking does not mean they are thinking correctly. Logic is like math, you have to get it right if you want the right answer. So how does someone think correctly?
Lucky for us, people have been thinking about thinking for thousands of years. The ancient Greek superstars such as Socrates, Plato and Aristotle discovered many of the rules to logic. A lot of what they established is still taught in Critical Thinking and Basic Philosophy classes today.
Here are the basics of logic: propositions.
A proposition is something you propose. For example: “Kobe Bryant is a man.” This is either true or false. When I am building a logical argument, I need at least two propositions. This is like basic addition in mathematics. I can’t add if I only have one number. I need at least two numbers added together to get my answer. In logic, we use 2 or more propositions to get to our answer. The answer is called the conclusion. The 2 or more propositions used in our argument are called premises. Here is an example:
Proposition 1 (aka premise): “Kobe Bryant is a man.”
Proposition 2 (aka premise): “All men are mortal.”
Conclusion: “Kobe Bryant is mortal.”
If we agree that both premises are true, we then attempt to formulate a conclusion that logically follows the propositions/premises. Please note than in an argument, propositions (aka premises) are true or false, but the conclusion is either valid, or invalid. This is because the conclusion is not a premise but the attempt to draw logic from true premises.
The goal in logic is to deduce a conclusion from 2 or more premises. That’s it, that’s all. This is also called “deductive reasoning.” We need to follow the rules of logic so that our arguments are proper (i.e.: valid conclusions).
Inductive reasoning is different than deductive reasoning. It can be said to work with probabilities instead of certainties. Television crime dramas are examples of detectives using induction to find suspects using crime scene evidence. The clues at the scene can be labelled premises, but finding “who dunnit” is a matter of narrowing probabilities based on the premises (i.e.: crime scene evidence). For example:
Proposition (aka premise): “80% of the swans living around Lake Etobicoke are white.”
Proposition (aka premise): “The swan that stole blind Ms. Burton’s hat was at Lake Etobicoke.”
Conclusion: “The swan that stole Ms. Burton’s hat was probably white.”
As you can see, we are not dealing with iron clad, inescapable conclusions but the building of a likely scenario. Inductive reasoning is only used when deductive reasoning is not available. Most of the time, you will be working inductively because life rarely offers absolutely clear, deductive options. Where did you leave your keys? The narrowing process would begin by looking at where you usually put them. There would be no absolute, deductive way of finding them inescapably. Make sense?
Whether you use deductive or inductive reasoning, you could have an army of true premises but if you commit an error in your logic, you won’t string them together to form the accurate conclusion. Now that you know the anatomy of an argument, knowing what good logic is will help you to deduce a valid conclusion. A key to sharpening your logic is to know what bad logic is and avoid it. Bad logic is often referred to as “logical fallacy.” Let us turn our attention to some examples of poor thinking.
The Nizkor Project website contains a fairly comprehensive list of logical fallacies and is a good resource for those looking to “tighten up” their thinking.
One of the classic errors in logic is one we see most often during political debates. It is known as the Ad Hominem logical fallacy. This is when one person attempts to dishonour their adversary’s reputation instead of debating them. For example, Politician A states that the unemployment rate has gone up by 4% during Politician B’s tenure. Instead of tackling this head on, Politician B points out that Politician A was caught having an extra-marital affair.
What is being attempted here is to smear Politician A and therefore making the audience less likely to trust him and anything he says. However, this is an error in logic. It is very possible for a dishonest man to point out the truth. How dishonest Politician A has been in his marriage has nothing whatsoever to do with the unemployment rate. Politician B has left the world of logic and entered the world of fallacy and error. We should be careful to not follow him.
Anatomy of an Ad Hominem:
- Person A makes claim X.
- Person B makes an attack on person A.
- Therefore A’s claim is false.
Whenever a Christian leader falls into sin, we often hear non-believers denounce the Christian faith as a result. This is a clear case of Ad Hominem. All it does is point to one individual’s personal choices. This is a totally invalid conclusion built on true propositions. Let’s break the argument into its components to highlight the logical fallacy at play:
premise 1: Jimmy Swaggart hired a prostitute
premise 2: Jimmy Swaggart is a Christian
conclusion: Christianity is false
This is why understanding the rules of logic is so helpful. The above breakdown of the Ad Hominem attack shows that it is stating two premises that are true but the conclusion is not supported by logic. It is, in fact, devoid of any logical connection to the premises. It forms an argument with no evidence that could possibly discredit the historical case for the Resurrection, the reliability of the New Testament or any other line of reasoning used to support the Christian faith as intellectually viable.
Another common logical fallacy is the Appeal To Authority.
An Appeal to Authority is a fallacy with the following form:
- Person A is (claimed to be) an authority on subject S.
- Person A makes claim C about subject S.
- Therefore, C is true.
We see this often when the discussion of evolution takes place in a television program or public debate. Typically the person arguing in favour of Darwinian Macro-evolution will name one or more prominent scientist and proudly report that they have accepted the theory as fact.
What could and should be pointed out is that there is a long list of high level biochemists, biologists and paleontologists who do not accept the claims of Macro-Evolution. When and how do we decide whose side has the most authority? This would be nearly impossible and more importantly, it would tell us nothing about the truth content of evolutionary theory. A simpler approach would be to look at the evidence itself and allow it to have the highest authority. Afterall, this is exactly how science works.
Often, another logical fallacy is heaped on top of an Appeal to Authority. The Appeal to Popularity is a common bed fellow. The Appeal to Popularity has the following form:
- Most people approve of X (have favorable emotions towards X).
- Therefore X is true.
A pro-evolution debater will state that most modern scientists believe in evolution. The audience will be impacted by this and be tempted to accept what “most people are doing.” It is an unfortunately deeply human flaw to lemming oneself with the crowd. An obvious repost to the Appeal to Popularity in the evolution/creation debate is to point out that, at one time, when the Church was the intellectual and cultural authority over Europe, the most prominent intellectuals did not believe in evolution.
Clearly, the authority of those intellectuals did not falsify evolution (if evolution is true) and likewise, simply because we’ve swapped sides in our day does not mean the modern majority has magically caused the universe to shift realities.
Whether or not evolution is an accurate account of life’s appearance and consequent growth, innovation and diversification should be assessed merely on the evidence, not by pointing out which celebrity intellectual believes something or how many friends he has doing it too.
As you can see, thinking properly is key to making sure that what you believe is accurate. Afterall, we watch what we eat, who we make friends with and what we let our children watch on T.V. Why not be diligent with what we believe? Especially when it comes to important subjects that deeply affect our lives.