Careful Conversations: Craft Sound Arguments

The third theme I noticed in my attempts to create careful conversations with those who disagree had to do with the structure of my arguments themselves.

The truth is you won’t get very far in conversations with others if they don’t consider you a sound “debate” partner; eventually, they will no longer give you the time of day.

So, how does one learn how to structure arguments properly?

“Therefore”

The truth is that this blog post could be an entire book. In fact, many books have been written on how to understand logic and craft sound arguments.

For a basic introduction written by a friendly voice, check out Jason Lisle’s book, Introduction to Logic.

But since our space here is limited, I will try to distill this down to the basic principle: An argument only works, ultimately, if you can place the word “therefore” in between a set of premises and the conclusion you reach, and that conclusion follows logically.

In other words, if I can’t listen to your reasons and, from them, find the logical path to your conclusions, the argument is a bad one. Let’s look at an example.

“There are parallels between Document A and Document B. Therefore, Document B was copied from Document A.”

The problem is that it is not necessarily the case that Doc B was copied from Doc A, even if there are similarities and/or parallels.

This argument simply fails to communicate enough information. It could be that both were written by the same author. Or, it could be that both authors found themselves in a similar circumstance when penning their documents. Or, it could even be that both authors were communicating original information, but started with the same prior source.

Thus, more work needs to be done.

What might that work look like?

Well in this example I can think of a few things:

1. A legitimate parallel must first be established. To see a similarity between documents is not the same as seeing a genuine parallel between them.

2. Direct evidence of copying must be found. You must be able to demonstrate via linguistic techniques, a study of the cultural milieu, and a thorough review of the documents themselves that there was direct copying going on.

3. There must be unidirectional causality between the two documents. This simply means that you must show that the parallel has a one-way causal direction; in other words, there is definitive evidence that Doc B was created and copied from Doc A.

Many more examples abound, but if you’re going to learn to craft sound arguments, you need to learn that such arguments will follow logically from the premises.

Informal vs. Formal Logic

What I’ve just given you is an example of “informal” logic. It can be harder to spot issues in informal logic than what is called “formal” logic, but most conversation is carried out “informally” so you will need to learn how to maneuver there.

Let’s look at a sound example of formal logic:

1. Premise 1: Socrates is a man.

2. Premise 2: All men are mortal.

3. Conclusion: Therefore, Socrates is mortal.

Now, how about this:

1. Premise 1: Socrates is a man.

2. Premise 2: All men are cats.

3. Conclusion: Therefore, Socrates is a cat.

As you can see, it’s much easier to spot potential errors in reasoning using formal logic in most cases (though not all). In the above example, the structure (form) of the argument is valid. But the arument itself is unsound because premise two is not true.

A sound argument will have a valid form and true premises.

Piecing it Together

One exercise you may find helpful is restating an informal argument as a formal argument, to help you determine whether or not the argument is true.

Let’s return to our example of copied documents. Stated formally,¹ The argument goes like this:

1. Premise 1: If Document B shares parallels with Document A, then Document B was copied from Document A.

2. Premise 2: Document B does share parallels with Document A.

3. Therefore, Document B was copied from Document A.

The form of this argument is valid. However, the argument may or may not be sound. The soundess of an argument depends, again, on the truthfulness of the premises.

As argued above, it’s not true that if a document merely shares parallels with another that it is evidence of copying. Not only would you have to establish that the parallel exists, but even if it did, much more information is needed to determine if legitimate copying took place.

As you can engage in conversations with others, be careful to hold others to sound logic, and hold yourself to it as well. A conversation rife with illogical arguments will never advance the conversation.

1. This would be called a Mixed Hypothetical Syllogism.