I would like to further narrow the scope. Systems are only useful under two prior conditions. First that they are constructed rationally upon sound premises and with the input of accurate information. Second, that they operate strictly within their proper framework (problem space as you put it) and don't go beyond it.

Further, I should insist that this reveals the importance, difficulty and danger of metaphysical speculation. It also explains the innumerable monumental errors leveled as the One True Way (patent pending) from the pre-Socratic ruminating on ontology to the present. It would, however, be an equally monumental error to eradicate metaphysical thought altogether, given these very difficulties. I say that anyone seeking the truth must in fact go forth all the more courageously, but learning from others' mistakes that one does not repeat them, with caution as well.