How did William of Ockham’s views about universals differ from those of John Duns Scotus?

The views of John Duns Scotus and William of Ockham regarding universals represent a fundamental shift in medieval philosophy from realism to nominalism.

For Duns Scotus, common natures (such as humanity) are real and possess a genuine unity distinct from the individuals in which they exist. He argued that while universals exist as abstract concepts, they are grounded in these real common natures. To explain how these natures become specific individuals, he introduced the concept of "thisness" or haecceitas, an added positive reality that differentiates one individual from another.12

In contrast, William of Ockham rejected the existence of such common natures. He argued that there are no realities other than individual things and that these things have nothing in common. For Ockham, universal concepts are not based on real, shared essences but are merely mental tools used to categorize things that are more or less similar to one another. This rejection of real universals, often associated with Ockham’s razor, reflects his commitment to the absolute freedom of God, who creates individuals directly without relying on preconceived universal models.3