“Russell’s point is not to assert his right to be left alone to his personal delusions, but that devising a theory that cannot be proved or disproved by observation is pointless in the sense that it teaches you nothing, irrespective of how passionately you may believe in it. You can invent any object or idea you like, but if there is no way of observing it or its consequences, you haven’t made a contribution to the scientific understanding of the universe.”