How can Occam’s razor support both physicalism and dualism in philosophy of mind?

Occam’s razor, a principle attributed to the English philosopher William of Ockham, posits that "plurality should not be posited without necessity". In the philosophy of mind, this heuristic is used to support competing views by prioritizing different types of simplicity.123

Physicalism and Ontological Parsimony

Physicalism is often defended using the principle of ontological parsimony. By reducing mental states to physical processes, physicalism requires only one type of entity—matter—to explain reality. This is seen as simpler than dualism, which necessitates the existence of two distinct elements: mind and matter.3

Dualism and Syntactic Simplicity

Conversely, dualism can be argued as more straightforward in terms of syntactic simplicity. While physicalism reduces mental states to physical ones, it may be viewed as less elegant because it requires us to conceptualize what appear to be two fundamentally different kinds of entities as ultimately being one. Because Occam’s razor can be interpreted through these different lenses, it remains a contentious guiding heuristic rather than a definitive proof for either position.3