What are syntactic simplicity and ontological parsimony?

In the context of the philosophy of William of Ockham, the principle known as Occam’s razor is often analyzed through two distinct types of simplicity.1

Syntactic Simplicity

Syntactic simplicity refers to the elegance and conciseness of a theory itself. A theory possesses this quality when it relies on fewer assumptions or is more straightforward in its formulation compared to competing theories.1

Ontological Parsimony

Ontological parsimony relates to the nature of the objects or entities a theory seeks to explain. It prioritizes simplicity regarding the number of fundamental entities or phenomena required to account for reality. For example, physicalism is often cited as an example of ontological parsimony because it posits that reality consists of a single type of entity—physical matter—whereas dualism requires the existence of two distinct elements: mind and matter.1

While these concepts help guide scientific and philosophical inquiry, they are generally viewed as heuristics rather than absolute truths, as prioritizing simplicity can sometimes lead to the sacrifice of accuracy or result in conflicting interpretations.1