Intentionality is the property of mental states to be directed at or about something. It is what allows us to think about and refer to objects, events, and states of affairs in the world.

Franz Brentano is considered to be the father of the concept of intentionality. He argued that intentionality is the defining characteristic of mental states, and that it is what distinguishes them from physical states.

Phenomenal consciousness is the subjective experience of consciousness. It is what it is like to be conscious, to have thoughts, feelings, and sensations.

Thomas Nagel is most closely associated with the concept of phenomenal consciousness. He argued that phenomenal consciousness is a fundamental aspect of reality that cannot be reduced to physical processes.

Self-consciousness is the ability of consciousness to be aware of itself. It is what allows us to reflect on our own thoughts, feelings, and experiences.

René Descartes is most closely associated with the concept of self-consciousness. He argued that the self is a thinking thing, and that self-consciousness is the foundation of all knowledge.

The hard problem of consciousness is the problem of how physical processes can give rise to consciousness. It is considered to be one of the most difficult problems in philosophy.

David Chalmers is most closely associated with the hard problem of consciousness. He argued that the hard problem is a fundamental problem that cannot be solved by any physical theory of consciousness.

Epiphenomenalism is the view that consciousness is an illusion. It argues that consciousness is a by-product of physical processes, but that it has no causal efficacy.

Thomas Hobbes is most closely associated with the view of epiphenomenalism. He argued that consciousness is a mere shadow of physical processes, and that it has no real causal power.

Panpsychism is the view that consciousness is a fundamental aspect of reality. It argues that consciousness is not an illusion, and that it is present in all things, even inanimate objects.

Alfred North Whitehead is most closely associated with the view of panpsychism. He argued that consciousness is a fundamental aspect of reality, and that it is present in all things, even inanimate objects.

Materialism is the view that consciousness is a product of the brain. It argues that consciousness is a physical phenomenon, and that it can be explained by the laws of physics.

Karl Marx is most closely associated with the view of materialism. He argued that consciousness is a product of the brain, and that it is determined by the material conditions of existence.

Dualism is the view that consciousness is a non-physical substance. It argues that consciousness is independent of the brain, and that it can exist without it.

René Descartes is most closely associated with the view of dualism. He argued that consciousness is a non-physical substance, and that it is independent of the brain.