In other words, a good argument gives us a compelling reason to believe its conclusion. A deductive argument is valid just in case the truth of its premises would guarantee the truth of its conclusion. A sound argument thus constitutes a proof of its conclusion. Nondeductive arguments never prove their conclusions, nor are they deductively valid. Rather, a nondeductive argument is said to be stronger or weaker .
Strength is a matter of degree.
Polling is a good example. If your initial sample is too small, your argument will be weak. Likewise, if your initial sample is biased, your argument will be weak. Therefore, probably Jill is rude. The strength of an analogical argument depends on several factors.