Number of attributes
Spinoza's contemporary, Simon de Vries, raised the objection that Spinoza fails to prove that substances may possess multiple attributes, but that if substances have only a single attribute, "where there are two different attributes, there are also different substances".[31] This is a serious weakness in Spinoza's logic, which has yet to be conclusively resolved. Some have attempted to resolve this conflict, such as Linda Trompetter, who writes that "attributes are singly essential properties, which together constitute the one essence of a substance",[32] but this interpretation is not universal, and Spinoza did not clarify the issue in his response to de Vries.[33] On the other hand, Stanley Martens states that "an attribute of a substance is that substance; it is that substance insofar as it has a certain nature"[34] in an analysis of Spinoza's ideas of attributes.
Misuse of words
Schopenhauer claimed that Spinoza misused words. "Thus he calls 'God' that which is everywhere called 'the world'; 'justice' that which is everywhere called 'power'; and 'will' that which is everywhere called 'judgement'."[35] Also, "that concept of substance...with the definition of which Spinoza accordingly begins...appears on close and honest investigation to be a higher yet unjustified abstraction of the concept matter."[36]
