What is the doctrine of psycho physical parallelism as discuss by spinoza?

Answer 1

Spinoza's philosophy contains as a key proposition the notion that mental and physical (thought and extension) phenomena occur in parallel, but without causal interaction between them. He expresses this proposition as follows:The order and connection of ideas is the same as the order and connection of things.(E2P7)[3]

His proof of this proposition is that:The knowledge of an effect depends on, and involves, the knowledge of its cause.(E1A4)[3]

The reason Spinoza thinks the parallelism follows from this axiom is that since the idea we have of each thing requires knowledge of its cause, this cause must be understood under the same attribute. Further, there is only one substance, so whenever we understand some chain of ideas of things, we understand that the way the ideas are causally related must be the same as the way the things themselves are related, since the ideas and the things are the same modes understood under different attributes.