There has been a minor flurry of interest in Alan Turing in recent days, with the suggestion that his face appear on a new series of Bank of England £50 notes. No doubt this would be a splendid way to give further official recognition to the achievements of one of Britain’s greatest thinkers of the twentieth century, and to acknowledge the affection in which he is held by many people today.
But what is a £50 note for? Does anyone use them for savings? Does anyone get paid on Fridays in cash in a brown envelope still? Why would you carry bundles of paper around for a high-cost purchase? Retailers don’t like them and taxi-drivers won’t accept them. The unpleasant conclusion is that £50 notes may be used for transactions that are intended to stay hidden from view: keeping out of view of the tax authorities or the banks, which police money laundering. So the idea of associating Alan Turing with the darker side of the economy might be a mixed blessing.
What Alan Turing would have had to say about digital currencies is perhaps an interesting speculation. As a cryptology expert, he would have had some – probably trenchant – opinion on the security aspects of replacing a trusted central database operated by a bank with a community of peers solving crypto puzzles. Currencies are about trust, and the fluctuation of values of e-currencies perhaps implies a fluctuation of people’s perception of reliability. But one thing is certain: there is no chance of Alan Turing’s image appearing on a virtual coin.