Q: How do we know greater-than-human intelligence is possible?

A: Imagine a crowd of spectators seeing an airplane in flight for the first time – an early Wright Brothers model – and saying to themselves, “They’ll never top this.  That is the best airplane there will ever be.” Sound absurd?  It should, because it was obvious, even then, that airplanes would, in time, fly faster, higher, and farther, while carrying passengers and cargo.  They recognized the Wright Brothers’ plane as a first step, not the last.

The human mind is also a “young” design that could obviously be improved upon.

Consider our evolutionary origins.  The so-called “general intelligence” of human beings – the kind flexible enough for abstract thought, technological progress, artistic creation, etc. – is as young as a few million years, and reached it’s current form as recently as 50,000 years ago.  This may not sound very young until you reflect that evolution has been toying around with processes like photosynthesis for a few billion years.   In fact, if evolution kept a written journal (with 100,000 years per page), the general intelligence of modern man would appear only on the last page of a volume 38,000 pages long!

It is, therefore, hard to believe that the possibilities of general intelligence have been fully played out by evolution.  Given millions more years of unhindered natural selection, the intelligence of man’s descendants would surely be greater than our own to some measurable degree.

Consider also the constraints of confining the ccncept of evolution to Earth.  The universe is a very big place, and on some other world where life happened to evolve, it is not inconceivable that intelligence could appear along a very different path.  Life on Earth is carbon-based.   Along with all the other directions this might have gone (think spiritual algae or literate mushrooms), it is possible that life can evolve based on other elements, such as silicon.  Take this a step further; intelligent life which did not evolve (but was initially created by an evolved intelligence) might exist in an incalculable number of biological and non-biological configurations.   The probability of human minds representing the best and brightest among all these possibilities is remote.

There is no shortage of ideas for how minds could be made more intelligent than our own.  Discussion of these is best saved for other questions, but for now let it be said that the "faster, higher, farther" analogy to aircraft development may not be so far off.

It is true that we can’t predict exactly how a designed mind will look a century from now any more than the Wright Brothers could have designed a Boeing 747. But it is naïve – if not hubris – to believe that our current brains are the most intelligent structures that can ever exist.