Mark Trapp

Anatomy of an Argument

A few months ago, I discussed the value of discussing, not debating, ideas: that we should be focused on a person’s argument, not the person. Yesterday, I talked a little about a real-world application of a discussion of ideas, and the value of understanding an opposing argument before providing your own. Today, I’m going to go back to basics and discuss what, exactly, constitutes an argument, and how knowing how to spot an argument can help one form one’s own arguments.

What does an argument look like?

I’ve said previously that an argument isn’t a yelling match: it’s a rational justification for an idea. It’s more than that, though: when you make an argument, or you try to understand another person’s argument, you’re looking for three very specific things:

  1. Identify what the argument is trying to claim, and what facts it provides to support it (Premises and Conclusions),
  2. Figure out if the claim necessarily comes from the supporting facts (Valid Arguments), and
  3. Determine if the supporting facts are actually true. (Soundness)

Premises and Conclusions

The first step in understanding an argument is to identify two types of information. Firstly, you provide some information that one ought to take as being true, called premises, and secondly, you provide a conclusion drawn from those premises.

“I can see the Sun: it’s daytime” would be a very simple argument. The statement of fact, that it’s daytime, is dependent on my seeing the Sun being true, and that seeing the Sun does, in fact, indicate that it’s daytime. Another argument might be “I can see the Sun; therefore, the iPhone is a smart phone.”

Valid Arguments: necessity and sufficiency

This second argument is a little strange: the conclusion doesn’t have anything to do with the premise. That’s because the argument is not valid: a valid argument is one where the conclusion necessarily comes from the premises.

Necessarily is the operative word; the iPhone could be a smart phone: my (bad) argument doesn’t preclude that. In order to make good on my argument, I need to provide other premises that would enough to necessitate the conclusion. If I said, for example, “The iPhone can access the internet and do more than just make calls,” that’d be more likely to necessitate the conclusion, “the iPhone is a smart phone.”

On the other hand, the first argument, that because I can see the sun, it’s daytime, is a valid argument. In fact, the premise, “I can see the sun” is sufficient for coming up with the conclusion: based on that fact alone, the conclusion couldn’t possibly be false.

Necessity and sufficiency will play an important role in a later post, where I go into fallacies: for now, they act as a means for differentiating a valid argument from an invalid one.


The final thing to identify in an argument is its soundness. A sound argument is a valid argument that also consists of true premises. Consider the valid argument from above: “I can see the Sun, therefore it’s daytime.” That’s a valid argument: but what if I’m lying, and I can’t actually see the sun? Then the argument isn’t sound. It doesn’t necessarily mean the conclusion is false: it could be a cloudy day, after all. Note that the argument must be valid: “I can see the Sun; therefore the iPhone is a smart phone” could never be sound, even if the premise were true.

Wrapping Up

The three steps outlined are important: in fact, all arguments can be parsed with these three steps alone (obviously, each step has its own methods and tricks for completing them, more on that in later posts). Besides providing a foundation for understanding an argument, every bad argument can be defeated with at least one of the steps: either the argument doesn’t provide reasons for a conclusion, the conclusion doesn’t necessarily follow from the reasons provided, the reasons provided are simply false, or a combination of the three.

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