So last week I was thinking about presuppositional apologetics a bit. If you are unfamiliar then check out the wiki on it here - http://en.wikipedia.org/wiki/Presuppositional_apologetics
In essence, it is a class of arguments (typically from the Abrahamic traditions like Christianity and Islam) that want to suppose some "facts" as a basis for argument. The great failing of this method of thinking is that it is founded in circular reasoning (the "answer" supposes itself in the argument).
One YouTube video that I watched (https://www.youtube.com/watch?v=hGM5JM5A0E0) basically called out how it's become almost silly to debate or argue with presuppositionalists with any experience because things seem to quickly break down into a race to be the first one to invoke solipsism, thus rendering both arguments null (since we can't seem to be sure of anything).
I agree with the principal of the topic. As soon as someone invokes solipsism we are all "caught" in a solipsistic loop of no one being able to get out of. If I can't know anything for sure, then how can you. I think that (as the speaker in the video points out) it results in a zero sum game that no one is really supposed to win.
I, however, think that there is a way out of the solipsistic hole. I think that the arguments can move back to what is functional over what is possible, then this doesn't have to be a true impasse. Solipsism doesn't have functional value beyond possibility. In fact it rarely reaches into probability, and never seems to work itself into observation.
Solipsism, from wiki - http://en.wikipedia.org/wiki/Solipsism, is the idea that we can't prove anything outside of ourselves. While this may or may not be true, it lack function in the real world. If I truly believe that the only thing I can prove is my own mind, then why stop at red light? Why not try flying unaided? Why not spend every last cent you have on decorative bakeware and velvet cat paintings? The answer is rather silly seeming to all of these questions and that is the point. All of those actions will have consequences that are not beneficial. Our combined experience in the "world", as much as it is subject to falsification, trickery, illusion and phenomena, is still reliable enough be useful in predicting outcomes of events as we experience them. AND that experience, by comparison to others, seems to be shared and equally relevant to them. Thus our senses and experiences with those senses have been shown to be trustworthy, as well as the quantitative experiences of others (such as we can both use a ruler to measure one foot, for example, and it would end up being (with a relatively small margin of error) the same thing.