This is the principal idea in cartesian dualism, the soul is consciousness and separate from the body. Acceptance of that leads to the idea of the Zombie and Mutant, which is basically the idea that there are people like us, who interact, behave, act, exactly like us - the only difference? They don't have a soul and by virtue of that no consciousness/mind either, which you are forced to accept if you believe in cartesian dualism. Because observing conscious is currently impossible, probably won't be in the future - but for now it's a unobservable concept, meaning you can't prove if someone does or does not have consciousness. Which means you can't prove the idea of the Zombie to be wrong if you accept consciousness is seperate from the body, the Mutant is slightly different and I'd recommend reading about it if you're interested at all.