Physical events can cause other physical events and physical events can cause mental events, but mental events cannot cause anything, since they are just causally inert by-products (i.e. epiphenomena) of the physical world.
Peristiwa fisik dapat mengakibatkan peristiwa fisik lain dan peristiwa fisik dapat mengakibatkan peristiwa budi, namun peristiwa budi tak dapat mengakibatkan apa-apa karena mereka hanya epifenomena dunia fisik.