The Three Tests to a Good Argument

According the the Critical Thinking textbook, an argument is good if it meets three criteria:

1) The premise must be plausible.

2) The premise must be more plausible than the conclusion.

3) The argument must be valid or strong.

Carl Sagan wrote about an invisible dragon in his garage. The invisible dragon can breathe heatless flames, and is incorporeal. Sagan writes, "what's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there's no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists?" Essentially, what he is saying is that the argument is pointless if the premise cannot be proved.

Since the premise is the opposite of what one could consider plausible, the argument is rendered bad. The second rule, that the premise must be more plausible than the conclusion, also fails. The conclusion that dragons exist based on the idea that they cannot be detected in any way does not prove that they exist.

The third rule, that the argument must be valid or strong, does succeed. Let's look at the premise and the conclusion again.

Premise:

"There is an invisible dragon in my garage that cannot be detected by any physical means."

Conclusion:

"Dragons exist, they just can't be seen, felt, or heard in any way shape or form."

So, this argument would be valid, but a weak argument because it can't be proven since the invisible dragon is undetectable.

This argument is valid. Thus, it succeeds on the third rule.