Qualia are the subjective, conscious experiences of qualities that cannot be fully described or explained in objective terms.

Plato's Idealist Theory posits that reality is fundamentally mental or spiritual, and that the physical world is a mere reflection of the ideal world.

In Idealism, the physical world is seen as a product of the mind or consciousness, rather than an independent, objective reality.

One of the main objections to Idealism is that it struggles to explain how multiple minds can exist and interact in a shared world.

John Locke introduced the idea of 'sense-data' as mental representations of physical objects, arguing that these sense-data are the direct objects of our perception.

Solipsism is the extreme form of Idealism that asserts that only one's own mind exists, and that the external world is merely a product of one's own consciousness.

René Descartes proposed the concept of mind-body dualism, arguing that the mind and the physical world are two separate substances that interact through the pineal gland.

Epiphenomenalism is the view that mental phenomena are byproducts of physical processes and have no causal influence on the physical world.

Immanuel Kant's transcendental idealism posits that the mind imposes its own categories and structures on experience, shaping the way we perceive and understand the world.

Materialism is the view that the physical world is the only reality and that mental phenomena are products of physical processes.

John Locke's empiricist theory posits that the mind is initially devoid of knowledge and that all ideas and concepts are derived from sensory experience.

Dualism is the view that the mind and the physical world are two distinct substances with different properties and characteristics.

David Hume's materialist theory posits that the mind is a product of the brain and that mental phenomena are reducible to physical processes.

Materialism is the view that the physical world is the only reality and that mental phenomena are products of physical processes.

Baruch Spinoza's monist theory posits that the mind and the physical world are two aspects of a single, underlying substance, which he called 'God' or 'Nature'.