A “principle justify” question is one that asks you to identify a principle that, if added to an argument, would cause the argument to be valid (the conclusion is logically inferred from the premises). The question stem for a principle justify question might read:

  • Which of the following principles, if valid, most helps to justify the reasoning above?
  • Which of the following is a principle that, if established, would most justify the reasoning in the argument above?
  • Which of the following principles, if valid, most helps to justify the reasoning above?

We solve these questions by following four steps:

  1. Identify the argument’s conclusion.
  2. Identify how the conclusion is supported.
  3. Identify the gap in the argument’s reasoning
  4. Choose the answer that bridges the gap in reasoning.

Let’s take a look at each step.

Identify the Conclusion

The main conclusion of the argument is supported by everything else in the argument; it’s what the rest of the argument is attempting to convince you is true. If you struggle with identifying conclusions, take a look at the Identify the Conclusion Questions lesson.

Identify How the Conclusion is Supported

Make a note of the premises. What supports the conclusion? Why does the author think we should believe the conclusion? Silently paraphrase the support to yourself, trying to understand why the author finds the premises to be so convincing.


Identify the Gap in the Argument’s Reasoning

Principle justify questions never provide us with valid arguments; the premises do not necessarily lead to the conclusion; something is missing from the argument. This is because principle justify questions are really just sufficient assumption questions in disguise. All you need to do is pinpoint the gap in reasoning (just like with a sufficient assumption question) and fill that gap with a principle.

Choose the Answer

Find the answer that fills the gap in the argument. The correct principle will connect the support to the conclusion and create a solid argument.

Principle Justify Questions

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