Wikipedia: Good argument

Good argument, as one sees it used by philosophers and many others, means simply a sound or else a strong argument. If one has offered a sound or strong argument in defense of one's conclusion, then one has stated a true view, or at least a probably true view. The premises of one's argument support, or, with some sophisticated complications aside, justify? one's belief in the conclusion. That is why good arguments are so important: a good argument is the closest thing we have to a guarantee that a belief is true. If one is armed with a good argument, one has helped to justify one's belief in the conclusion, and to remove doubts about it.