What concept describes the idea that the mental and physical realms exist separately but in harmony?

The concept that describes the idea of the mental and physical realms existing separately but in harmony is known as Parallelism. This philosophical standpoint posits that mental and physical events correspond with each other without directly influencing one another. In the context of psychology, this means that while mental states (thoughts, feelings) and physical states (brain activity, bodily responses) are distinct, they operate in a coordinated manner.

Parallelism contrasts with other concepts like Dualism, which asserts that the mind and body are fundamentally different substances that interact, or Interactionism, which holds that mental states can affect physical states and vice versa. Holism, on the other hand, suggests that systems should be viewed as integrated wholes rather than just a collection of parts, which does not align with the clear separation implied in Parallelism. Hence, the emphasis on harmony without direct interaction underlies why Parallelism is the correct answer in this context.