Evaluating Evidence
Now that you are able to separate the conclusion from the premises that support it, it is time to evaluate those premises. This is a vital step; the conclusion, after all, is trying to convince you of something-that you should accept a certain opinion, change your beliefs, or take a specific action. Before you accept that conclusion, therefore, you need to examine the validity of the evidence for that conclusion.
Specifically, there are three questions to ask yourself when evaluating evidence:
1. What type of evidence is offered?
2. Is that evidence credible?
3. Is that evidence reasonable?

Types if Evidence
There are many different types of evidence that can be offered in support of a conclusion. One of the most basic distinctions to make is between premises that are fact, premises that are opinion, and premises that can be accepted only as tentative truths.
Here is a review of the difference between fact and opinion:

• A fact is something known for certain to have happened, to be true, or to exist.
• An opinion is something believed to have happened, to be true, or to exist.
• A tentative truth is a claim that may be a fact but that needs to be verified.

Whether they are facts, opinions, or tentative truths, premises can come in the following forms:

• Statistics or figures
• Physical evidence (artifacts)
• Things seen, felt, or heard (observations)
• Statements from experts and expert witnesses
• Reports of experiences
• Ideas, feelings or beliefs

Some types of evidence seem more convincing than others. That is, people are often more likely to believe or be convinced by statistics than by someone's opinion. But that does not mean that all statistics should automatically be accepted and that all opinions should be rejected. Because statistics can be manipulated and because opinions can be quite reasonable, all forms of evidence need to be examined for both credibility and reasonableness.