Ockham famously rejected the existence of anything metaphysically universal outside the human mind; he was an uncompromising nominalist in the mediaeval debate on universals. His rejection followed, not from his razor, but from his conviction, supported through long argumentation, that the very idea of a ‘universal substance existing outside the mind’ was simply incoherent, contradictory, or false. No adequate theory of this idea had been or could ever be given; everything outside the mind is irreducibly individual, not on account of some distinct individuating force, as Scotus had said, but simply in se ipso. On his view, the only things in reality that could in any way be truly denominated ‘universal’ are the general concepts existing in the human mind, for example the concept man or the concept white. The general concept white is universal, but only in the following reduced, metaphysically innocuous sense: white applies to many individual things.