As I suggested in the previous post, we come to understand something better through a number of arguments rather than through a single argument.
Suppose you prove your position through a single argument that seems strong to you. In this case there is a second-order consideration which significantly weakens your argument. Namely, if you already suspected or held a position, or if you wanted it to be true or to believe it, how likely is it that you would manage to find at least one argument in favor of that position which seemed strong to you, given that the position was false? It is probably not much less likely than the same thing given that the position is true, and so the strong argument should not increase your belief in that position by very much. This of course does not imply that you should ignore the content of the argument, but it does mean that you should take it with a bit of caution. Approaching the matter with many arguments weakens this second-order consideration and gives you more reason to accept the implications of the arguments.
Using a number of arguments also helps you to refine your view, making it more precise, giving you a better ability to resolve objections, and so on. This is certainly one of Aristotle’s reasons for proposing the use of dialectic in coming to understand, and a reason for the use of many arguments in disputed questions, as I said in the previous post.
On the other hand, even if you come up with multiple arguments for your position, this may not be very helpful if you ignore opposing evidence, and so it is necessary to construct arguments against your position as well. This is the reason that a disputed question has arguments on both sides.
If you manage to construct a large number of arguments on both sides of a position, this will often give you a very strong basis for judging the truth of the position. It is difficult to assign numerical probabilities, and consequently to determine the exact strength of the evidence or of an argument for a position. But it is often comparatively easy to see the relative strength of two pieces of opposing evidence, or two opposing arguments. Consequently once such a list of opposing arguments has been constructed, it is possible to look at one side and see how the arguments compare to those for the other side.
As I have said earlier, there is evidence for any position, whether it is true or not. However, the evidence for a false position generally tends to be weaker than the evidence for a true position. So for example if nearly all the arguments for one side of a position are fairly weak, while many of the arguments for the other side seem significantly stronger, we can get a pretty good sense of which position is true and which is not.
On another note, there is a good post against the Equality Dogma here.