The mechanist's dilemma
The Lucas argument can be restated as a dilemma about consistency (see detailed text).
Consider some arbitrary machine M:
Either: M is consistent,
In which case, by Gödel’s theorem there will be a sentence that humans recognise as true but that M can't prove. So, we can do something that machine M can't.
Or, M is not consistent
In which case, M can't be a mind because minds must be consistent systems.
In either case, the machine can't be a mind.
John Lucas (1961).