The use of computers has pervaded the life of every human being. At every street corner there are
machines to be found that have been designed to simplify our lives and take over the mundane jobs that
no longer require human intervention. One only needs to think of automated teller machines replacing
bank tellers, vending machines phasing out street vendors, or near-infallible CCTV watching over us as
policemen and sheriffs once did, to realise the extent that technology has enhanced and improved our
Given the speed and effectiveness with which computer technology has become a regular part of
our lives, it is not surprising that there is much speculation about the future implications of these
developments. One possibility that has stirred controversy is the suggestion that with the rate at which
computers are becoming ’smarter’ and better adapted, they may one day attain consciousness. This
concept has gained notoriety in popular culture, with films such as The Matrix, Ghost in the Shell,
2001: A Space Odyssey, and even the children’s show My Life as a Teenage Robot dealing with different
applications of this concept.
There is some scientific support for the idea that computers may one day become powerful enough
to simulate consciousness. For one, computing power has increased exponentially over the past decades.
Secondly, a Turing machine - a theoretical model of a computer, devised by Alan Turing, which would be
able to compute mathematical functions without any of the limitations that apply to physical machines
- would theoretically also be able to compute consciousness. This, of course, relies on the assumption
that consciousness can be somehow derived from mathematical functions - a controversial one in itself.
The question whether consciousness is Turing computable will be thoroughly explored in this paper.
The question of consciousness
In order to determine whether it is possible to compute consciousness, it is first necessary to define
consciousness. This in itself is something that scientists and philosophers have struggled with for ages.
For the purposes of this paper, the definition proposed by [Searle, 1998] will be used:
Consciousness consists of inner, qualitative, subjective states and processes of sentience or
awareness. Consciousness, so defined, begins when we wake in the morning from a dreamless
sleep - and continues until we fall asleep again, die, go into a coma or otherwise become
The difficulty with this definition with regards to the Turing computability of consciousness is that it
defines the existence of a subjective state as a prerequisite for consciousness. According to Searle’s
Chinese room argument [Searle, 1980], the fact that a system produces the same output as a conscious
mind would in response to the same input does not prove the presence of subjective consciousness.
However, this same argument can be used in...