David Bentley Hart at The New Atlantis:
But, of course, there is no reason for believing any of this; and it seems far more likely that the process of replacing one’s neurons with computer chips would be little more than a very slow process of suicide, producing not the same behaviors as would a living mind, but only progressive derangement and stupefaction, culminating in an inert mass of diffusely galvanized circuitry. After all, any sober phenomenology of the full range of mental acts discloses a host of necessarily unified features that are almost by definition irreducible to a mere integration of diverse mechanical parts and discrete functions, and that no process of computation could reproduce: subjectivity as an indissoluble privacy; the unified and simultaneous field of apprehension belonging to that subjectivity; qualitative consciousness; intentionality and its intrinsic teleology; the indeterminate openness of the mind to novelty and even to fundamental revisions of its conceptual paradigms, which no computational algorithm could simulate; the immediate physical sense of self; the psychological sense of identity; judgments of value, such as “good” or “true” or “beautiful”; the prior and constant disposition of the mind toward these values, which seems to be the necessary motive of all movements of intellect and will toward the world; creative violations of rules that nevertheless make “sense” to us; and so on.
more here.