stances” means facts of experience; and so experience decides about the truth or falsity of propositions, experience “verifies” proposition, and therefore the criterion of the solubility of a problem is its reducibility to possible experience. We can know what is verifiable. A question is a “good” one if we can indicate the way to its verification by possible experience — although, for some practical reason, we may be unable to follow that way.
Before speaking about those problems that are held to belong to the strictly unanswerable kind (i. e. by some philosophers, for there is no general agreement on this point), let us ask if there are perhaps any answerable questions the criterion of which does not lie in experience? These would evidently go beyond the realm of experience; the propositions answering them would have to be verified in some other way, they would deal with facts outside and independent of experience.
Many thinkers believe that such problems and such solutions exist; the field beyond experience with which these questions and answers are concerned would be the field of “Metaphysics”, and the criterion which would assure us of the truth of those answers woud not be experience, but “reason.” The philosophers who believe that there are such truths which cannot be accounted for by experience but rest on reason, are called rationalists (ratio = reason), and it is natural for them to think that all the most fundamental philosophical truths are of this kind. Those who do not believe that We cannot have any real knowledge that is derived from our reason but maintain that it must always rest on experience are called Empiricists (empeiria = experience). We see from this explanation why the meta-physician is usually a rationalist at the same time, while the empiricist rejects the possibility of metaphysics, i. e. of any knowledge that would reach beyond the world of experience. It is true that in the history of philosophy we sometimes find intermediate points of view, so that the equations rationalist = metaphysician, empirist = non-metaphysician, are not quite correct historically, but those views are due to certain confusions which complicate the matter and with which we do not have to concern ourselves.
Usually both parties admit the existence of a certain boundary which walls in everything that is knowable by experience and separates it from the rest of the world. But the metaphysician believes that this wall can be scaled by our reason, while the empiricist believes this to be impossible
