Clavis Universalis

Arthur Collier's Clavis Universalis (1713) is a philosophical work where he argues that an external world does not exist independently of the mind. Similar to George Berkeley, Collier posited that what we perceive as external reality is dependent on our minds. He contended that the distinction between a perceived object and an imagined one is not based on externality, but on vividness of experience, which he found insufficient proof of independent existence.1

Collier further argued that the concept of an external world is self-contradictory. He believed that perceived objects exist only in relation to the perceiver's mind, not independently. This perspective, he suggested, leads to the understanding that all existence is dependent on God, the supreme substance. This philosophical stance is related to the broader problem of universals, which questions the nature of general concepts versus particular instances.12