The very best reasons for a belief make it certain, they guarantee it. Well, the reason that critical thinking is important is because,[br]since we're rational, we want our beliefs to be true.
Rational people want to have true beliefs, and they want not to have false beliefs.
So a key part of critical[br]thinking is learning to evaluate arguments to determine whether or not they're good or bad, that is, whether or not their premises support their conclusions.
The red argument is the first response that she gave, two premises, "I can't stand Monty" and "I[br]want to have a good time." And the conclusion is "Monty[br]won't be at the party." And the third argument,[br]which we'll put in purple, consisted also of two premises, "Monty's in Beijing" and[br]"He can't get from Beijing to the party in time, so[br]he won't be at the party." Now, as I indicated[br]before, the first argument is not good, while the[br]purple argument is good.
So I'm gonna put up here, on the left, the orange argument, which is the second response that your friend gave, "Monty's really shy" and[br]"He rarely goes to parties." On the right we'll put[br]the purple argument, "Monty's in Beijing" and "He can't get from Beijing[br]to the party in time." Both of them have the same conclusion, "Monty won't be at the party." Now, as I said before, both of these are good arguments, they both do give you reason to believe the conclusion, i.e., both of them have premises which support the conclusion, but there's an important difference between the two arguments[br]that I want to point out.
If you consider the purple argument, and think about what those premises say, you'll notice that if[br]those premises are true, if Monty's in Beijing,[br]and can't get from Beijing to the party in time, then it must be true that Monty won't be at the party. In such an argument, where the premises guarantee the truth of the conclusion, we call the argument deductive.
The second reason,[br]though, is a good reason to believe that Monty[br]won't be at the party.
If he's really shy and[br]rarely goes to parties, then it's probable that he[br]won't be at tonight's party.
Rather, here, what it is to[br]say that a reason is good is closely tied to the notion of truth.
So a good reason for a belief is one that makes it probable, that is, it's one that makes the belief likely to be true.