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Understanding 71

us to predict this future even though there is no clue from the motion of
Venus today. Understanding allows us to predict discontinuous events: a
system changing its state or a star running out of fuel.
We see the same predicament in stock markets. Stock markets
normally behave in a linear fashion but, when they go wrong; they go
very wrong. Recent recessions have been made much worse by the failure
of hedging systems to handle market disruption. Some even think the
crises were caused by the automatic trading strategies of these hedging
systems.
The quants – as mathematicians in banks are called – spend
considerable effort modeling financial instruments to show that if one
stock goes down, another will go up at the same time. If the stocks
are held together your investment is safe because, on average they will
remain constant. The problem with these correlations, which often hold
reliably for many years, is that when trouble hits they fall apart. Historical
correlations don’t give us understanding of the future: something that
was only meant to happen once in a million years has happened within
six months. As they say on your investment papers, past performance is
no predictor of future results.

Do Computers Understand?
Today’s computers don’t have our general-purpose ability to understand.
Watson was thrown off by badly formatted English. The human
contestants, by contrast, had no problem with this. Just how good would
Watson have to be, to call it – or should I say ‘him’ – intelligent? How
could I judge this had happened? Alan Turing proposed an ingenious
test in his 1950 paper Computing Machinery and Intelligence using ‘The
Imitation Game.’ We now call the Turing Test.
If we ask a series of questions to a computer and we cannot tell its
responses from those a human would give, then the computer is, for all
practical purposes, the same as a human. Since we are intelligent – or at
least we hope we are – the computer must also be intelligent. QED.
That’s all there is to the Turing Test. Puzzled? Let’s pick his argument
apart.
Imagine you are chatting away on Facebook with someone you
don’t know. They may have posted a photograph so you can see what they
look like. The photo might be a fake; you have no real way to tell. What
question would you ask the other ‘person’ to prove they were human and
not a computer? There are obviously some giveaway questions. Please
multiply the numbers 342,321 and 23,294 and give me the answer. This

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