Carl Sagan on Consciousness and the soul
Sagan regarded the soul as an untestable hypothesis and consciousness as a natural phenomenon produced by the brain.
Sagan approached the question of the soul with the same empirical standards he applied to any extraordinary claim. In The Demon-Haunted World, he argued that there is no credible evidence for an immaterial soul that survives bodily death. Every aspect of consciousness — personality, memory, emotion, perception — is demonstrably dependent on brain function. Damage the brain and you damage the mind; destroy the brain and, so far as the evidence shows, you destroy the mind.
He was sympathetic to the wish for personal immortality but insisted that sympathy is not evidence. The desire to survive death is one of the deepest human impulses, and Sagan understood its power. But wanting something to be true does not make it true, and the entire history of science consists of discovering that the universe is not arranged for human comfort.
Sagan also noted the progressive retreat of the soul hypothesis. As neuroscience has explained more and more of what the soul was once invoked to explain — emotion, memory, personality, moral judgment — the soul has shrunk to fill an ever-smaller gap. This pattern, Sagan argued, is identical to the pattern of all god-of-the-gaps arguments: the gap always closes, and the supernatural explanation always retreats.
“I would love to believe that when I die I shall live again, that some thinking, feeling, remembering part of me will continue. But as much as I want to believe that, and despite the ancient and worldwide cultural traditions that assert an afterlife, I know of nothing to suggest that it is more than wishful thinking.”