I’m currently reading the new edition of Michael Shermer’s Why People Believe Weird Things which is an excellent book debunking pseudoscience and superstition, from the man who is probably the best known media sceptic.

However, at one point, Shermer does trip over his own assertions. (I point this out in the same spirit as that of Bill Bryson, using examples of bad English that he found in guides to English usage in his own guide.)

Shermer is careful to first explain the difference between the scientific method and the way most pseudoscience is reported. (He doesn’t mention it, but I love Robert Park’s encapsulation of this in Voodoo Science as ‘data is not the plural of anecdote’.)

Shermer tells us that in science we should be scrupulous about giving data that goes against our theories, rather than being selective with the observations. But then, only pages later, he indulges in a little selectivity himself. In illustrating the recent growth of science and technology, he tells us that transportation speed has undergone a geometric growth. His list goes from stagecoach (1784) 10 miles per hour, through bicycle (1870) 17 mph, steam train (1880) 100 mph, airplane (1934) 400 mph, rocket (1960) 4000 mph, space shuttle (1985) 18000 mph to TAU deep space probe (2000) 225,000 mph. (I’ve skipped some entries, but this gives a feel.)

More than one bit of naughtiness here, I fear. The last entry isn’t human transport, so really can’t be counted – you might as well put the speed of a bullet in there. If you drop that last entry we have a graph that flatlines 22 years ago.

But, more worryingly, there is also a discontinuity in the data. Up to airplane, they are all modes of transport available to normal people. From rocket onwards, they are specialist devices not available to the rest of us. If you keep the more consistent comparison of generally available transport, the graph is much more interesting. It goes a lot higher than ‘airplane’, because in the 1970s we got Concorde taking us to Mach 2. But that was the last upward step. And since Concorde was withdrawn, the transport speed graph drops to less than half its previous value. So that geometric progression isn’t anywhere near so solid as Shermer’s figures suggest.

I don’t do this to knock Shermer, or the book, just to point out the difficulties that come with being a sceptic. (Or should I say skeptic, as the book has US spelling. I just love reading the word ‘skeptic’ because to UK eyes it looks so seventeenth century, a bit like spelling optics or physics with a k rather than a c – I’m sure the reverse is true when US readers see some of our spellings.)