Holds that past, present, and future are all equally real, laid out together in a single four-dimensional ‘block’ of spacetime — meaning the flow of time from present to future is a feature of human perception rather than of the universe itself.
A middle position holding that the past and present are real, but the future does not yet exist at all — reality is a spacetime ‘block’ that is continuously growing as new moments come into being at its leading edge, the present.
A thought experiment arguing that a computer executing a program — however convincingly it behaves — cannot be said to genuinely understand, have a mind, or be conscious, regardless of how human-like its output is.
Searle’s own positive theory of mind: consciousness is an ordinary, higher-level biological feature caused by specific neurophysiological processes in the brain — comparable to how digestion is a biological feature of the stomach — real and physical, but not reducible to abstract computation alone.
Holds that the same mental state can be produced by different physical systems — meaning what matters for having a mind is the right functional organization, not the specific biological material it runs on, which in principle extends to silicon.
Argues that complex life requires an improbable conjunction of astronomical and geological circumstances, making simple microbial life plausibly common but complex or intelligent life exceedingly rare in the universe.
Holds that death is the permanent end of the person and of all experience — and, distinctively, argues this means death cannot actually harm the person who dies, since harm requires an experiencing subject and death leaves no subject behind to be harmed.
Proposes that some evolutionary or developmental step on the road from non-living matter to a galaxy-colonizing civilization is extremely improbable, “filtering out” almost every attempt — and that whether the filter lies behind us or ahead of us has very different implications for humanity.
Holds that a person consists of two distinct substances — a physical body and a non-physical mind or soul — and that because the soul is not made of matter, it is not necessarily destroyed when the body dies, leaving open the possibility of conscious survival.
Argues that a single spacefaring civilization equipped with self-replicating probes could colonize the entire galaxy within a few million years — a cosmic eyeblink — making the total absence of any such probes a strong argument against an older advanced civilization ever having arisen in our galaxy.