It is in areas like math and metaphysics that we encounter one of the average human minds’s weirdest attributes. This is the ability to conceive things that we cannot, strictly speaking, conceive of.

Consider the real history of Newton’s physics, compared to what might have been the history of Cartesian dualism. Newton’s physics reigned dominant for two hundred years. It gave us false beliefs but many benefits. I don’t think anyone will say ‘It would have been better if Newton had never lived!’ Imagine that Cartesian dualism had not been so conclusively rejected by the late seventeenth century but had also reigned for two hundred years. Would we say that the false beliefs that metaphysics gave us had been but a small price to pay for the ease and intuitive appeal felt in its explanation of the human condition?

The first procedure of a philosophy ought to be to expel things from consciousness and to reestablish its true connection to the world, to know that consciousness is a positional consciousness of the world.

I do not make the world that the thing gathers. I do not systematize the language in which the thing differs from all other things in the world. I testify to both, to acknowledge my need of both.

A philosopher is not a philosopher if he is not a metaphysician. And it is the intuition of being […] that makes the metaphysician.

Nature must be explained mechanically and mathematically, provided one bears in mind that the principles of the laws of mechanics themselves do not derive from mere mathematical extension, but from metaphysical reasons.

Philosophers constantly see the method of science before their eyes, and are irresistibly tempted to ask and answer questions in the way science does. This tendency is the real source of metaphysics, and leads the philosophers into complete darkness.

On the path of objective knowledge […] we shall […] remain on the outside of things; we shall never be able to penetrate into their inner nature, and investigate what they are in themselves. […] So far I agree with Kant. But now, as a counterpoise to this truth I have stressed that […] we ourselves are the thing in itself. Consequently, a way from within stands open to us to that real inner nature of things to which we cannot penetrate from without. It is, so to speak, a subterranean passage, a secret alliance, which, as if by treachery, places us all at once in the fortress that could not be taken by attack from without. Precisely as such, the thing in itself can come into consciousness only quite directly by itself being conscious of itself […].

Human reason has this peculiar fate that in one species of its knowledge it is burdened by questions which, as prescribed by the very nature of reason itself, it is not able to ignore, but which, as transcending all its powers, it is also not able to answer.

The denial of the existence of a transcendent external world would be just as much a metaphysical statement as its affirmation. Hence the consistent empiricist does not deny the transcendent world, but shows that both its denial and affirmation are meaningless.

This last distinction is of the greatest importance. I am convinced that the chief opposition to our view derives from the fact that the distinction between the falsity and the meaninglessness of a proposition is not observed. The proposition ‘Discourse concerning a metaphysical external world is meaningless’ does not say: ‘There is no external world,’ but something altogether different. The empiricist does not say to the metaphysician ‘what you say is false,’ but ‘what you say asserts nothing at all!’ He does not contradict him, but says ‘I don’t understand you.’