Steps 1 and 2 must be done first.

Step 1 .

Figure out the premises and conclusion. Put the argument in standard form: list the premises, then the conclusion. State any relevant unstated premises.

Step 2 .

Check CLARITY: Make sure you know what all the statements mean.

• Any objectionable vagueness?

• Any ambiguity (equivocation, amphiboly)?

• Any problems separating cognitive from emotive content?

• Any unfair slanting devices?

• Any problems distinguishing collective and distributive usage?

Steps 3 and 4 may be done only after you have done steps 1 and 2. You can do step 4 before step 3 if you prefer.

Step 3 .

Check LOGIC: Make sure that the premises support the conclusion. If the argument is deductive -- i.e., the arguer is claiming the conclusion must be true if the premises are true -- make sure the arguer is right (i.e., make sure the conclusion really must be true if the premises are true). If the argument is inductive -- i.e., if the arguer is claiming that the conclusion is likely if the premises are true -- then make sure the arguer is correct (make sure the conclusion really is likely if the premises are true). See “What is Bad Logic?”

• Any formal fallacies?

• Any informal fallacies (many)?

  NOTE: complex deductive arguments require formal techniques of symbolic logic to establish their validity or invalidity; i.e., assessing their validity or invalidity is beyond the scope of “critical thinking” classes. However, you can diagnose the validity or invalidity of a large number of common ordinary-language arguments with the methods described in “critical thinking” classes in Philosophy departments.

Step 4 .

Check FACTS: Make sure the premises are all true or reasonable to believe.

• Any false or dubious premises?

• Any relevant information omitted?

Final Evaluation .

If an argument is clear, omits no significant information, has good logic (no formal or informal fallacies), and all true premises, then the argument is likely most excellent! Reasonable people should accept its conclusion.