Arguments and Critical Thinking

An argument is an attempt to give reasons to believe something. For example:

Register everyone to be an organ donor. Organs benefit the living, not the dead.

An argument has two parts: the premises and the conclusion. The conclusion is what you should believe, and the premises are the reasons. Our example tries to convince you that everyone should be an organ donor. The reason: only the living benefit from having organs.

Critical thinking is about arguments. Do you know them when you see them? Can you take one apart? Put one together? Tell the good from the bad?

To test your skills, try a textbook exercise in critical thinking called standardizing an argument. You write an argument as an ordered list of declarative sentences—premises first, conclusion last, with the latter usually marked Therefore. This list is called standard form (or premise-conclusion form). It’s a standard way of showing clearly and exactly what’s being argued. Here’s a first go at standardizing our organ donation example:

1. Bodily organs benefit people who are alive.
2. Bodily organs do not benefit people who are dead.
3. Therefore, universal organ donor registration should be enacted.

Save for some philosophy professors and legal professionals, people rarely argue in standard form. Instead you tend to see:

• Premises and conclusions come out of order (as in the original argument, where the conclusion comes first).
• Some assumptions and inferences are left implied, leaving you to read between the lines (as we’ll do in a second go at standardizing our argument).
• Commands (“Save lives!”) and rhetorical questions (“Who wouldn’t want to save lives?”) express key ideas.
• Inessential information (“Fun fact: humans have more than 70 organs”) obscures the argument.
• Loaded, emotional language (“Give the gift of life or give the middle finger to the sick and dying”) does the persuading.

In contrast, standard form is orderly. It is explicit and declarative, focused and dispassionate.

So, standardizing an argument usually means remaking it. Where possible, you try to improve on the original, but only in terms of clarity, particularly when it’s someone else’s argument. Preserving the arguer’s meaning is paramount, and you strive to be charitable.

Back to our example argument. At least one more premise can fit. And a little visual styling couldn’t hurt, with Ps for premises and the “Therefore” sign (a three-dot triangle) to mark the conclusion:

This argument assumes implicitly that a registered organ donor donates at death. We’ve added that assumption as an unstated premise. The conclusion depended on it, but the argument left it out, so for clarity we filled it in.

You may suspect there’s more to fill in here. Which brings us, in textbook speak, to evaluating an argument. First, are the premises true? Second, even if true, are the premises relevant to the conclusion? Are they sufficient to support it or is something still missing? Think about it—critically.