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Navigating an Argument Map

Continuing with an introduction to argument mapping, courtesy of Nathan Otey, COO of ThinkerAnalytix

Last time, I introduced you to a simple map of an argument. An argument map is just a visualization of an argument structure that makes clear exactly how different reasons work together to support the main claim. The argument that I mapped last time made the case that you should learn how to map arguments. Today, I’d like to use that meta-argument example to explain how argument maps work.

Once again, here’s my mapped argument:

Every box in the argument map is called a claim and the main claim, the key point I want my argument to convince you of, appears at the top of the map (in box 1.1).

Below the main claim are premises that appear in the rest of the boxes in my map. A premise is just a statement that gives a reason to believe something. For example, the premises right below the main claim (2.1 and 2.2) answer the question “Why believe this?” about the main claim.

You’ll notice that this map is three layers deep. This illustrates that while the premises right below the main claim (level 2, including premises 2.1 and 2.2) give you reasons to believe the main claim, premises on the next level give you reasons to believe the premises above them. These relationships are represented by the lines which connect each claim in the argument to one or more reasons to believe that claim.

This map also illustrates three different kinds of premises, each of which can be visualized with argument maps. These include:

Co-Premises: Premises 2.1 and 2.2 are grouped under one green bracket because they are co-premises that work together, or “hold hands,” to provide one single reason to believe the claim above.

Sub-Premises: As I just mentioned, argument maps can “go deep” with some premises supporting other premises. In this case, 3.1 and 3.2 are sub-premises that each support premise 2.1. A sub-premise is simply a premise which gives a reason to believe another premise.

Independent Premises: Premises 3.1 and 3.2 are also independent premises, meaning that, unlike co-premises, they each provide separate, distinct reasons to believe the claim above. This means that if one independent premise is false, the other independent premise would still work as a reason to believe the claim above. This is in contrast to co-premises, like premises 2.1 and 2.2, where both statements have to be true in order to give you a reason to believe the claim above. Premise 3.3 is an also a sub-premise, one that supports premise 2.2.

These three basic premise types (co-premises, sub-premises, and independent premises) can be combined to visualize any argument, of any complexity.

The most important rule of Argument Mapping is the Reason Rule which says that every statement must always give a reason to believe the claim above it. Thus, every box in an argument map below the main claim should answer the question “Why believe this?” about the claim directly above it.

This is represented by the word “because” in the lines connecting claims in the map. These can be read downwards by, for example, stating the relationship between premises 2.2 and 3.3 as “Learning to map arguments will improve your critical thinking skills BECAUSE college courses in argument mapping improve critical thinking 6 times as much as a standard semester in college.”

When you focus on perfectly following the Reason Rule, you inevitably end up giving good reasons to believe your main claim. Which, of course, is the point of making an argument in the first place!

So far so good? In that case, let me introduce you to an argument about a real-world issue:

Think about the parts of the argument based on what you just learned about claims, the main claim, different types of premises, and the Reason Rule and I will return next time to show you how to analyze the argument contained in an argument map to see if it’s any good.


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