Asking if computers can think is like asking if submarines can swim

'Carbon lies at the centre of life, its ubiquitous and indispensable ingredient. Carbon atoms link together in chains, and bind with other atoms, to make the whole array of organic chemicals that constitute life itself, from DNA to toenails. Only one other atom is as versatile as carbon, and that is silicon, which comprises the essential ingredient of many rock-forming minerals. It, too, can hold hands with its neighbours through large molecules. Silicon chip technology exploits its properties, and it is not a coincidence that silicon intelligence is portrayed as the only possible rival to that of our own carbon-based brain.'
Richard Fortey

'Man is the best computer we can put aboard a spacecraft ... and the only one that can be mass produced with unskilled labour.'
Werner von Braun