Reality is the state of things as they actually exist, independent of perception or opinion. It is what is, not what seems to be. The question of what reality is and how we know it is one of the oldest in philosophy. Plato argued that true reality is the world of Forms, not the world of the senses. Aristotle argued that reality is the world we perceive, studied through observation. Descartes doubted everything until he reached the certainty of his own existence. Kant argued that we can never know reality as it is in itself, only as it appears to us.

Reality is not a single thing. It includes physical objects, minds, numbers, possibilities, and relations. Philosophers distinguish the real from the imaginary, the actual from the possible, the objective from the subjective. Debates about reality are not just academic. They shape how we think about science, religion, and everyday life. When someone says that a belief is out of touch with reality, they are making a claim about what is real. When scientists say that a theory describes reality, they are making a claim about what exists. Reality is the ultimate standard against which beliefs are measured.

Questions about reality

• What is real? Physical objects, minds, numbers, universals?
• How do we know? Perception, reason, intuition, science?
• Is reality mind-independent? Does it exist without observers?
• Is reality one or many? Monism, dualism, pluralism?

Reality is not the same as truth. Truth is a property of statements. Reality is what statements are about.