Numbers, The Fallacy of

The fallacy that if you cite precise numbers, particularly if they are large, you know what you are talking about. Example: a critic argues against taking action on climate change: “Estimates indicate that the total cost of global warming will be about $5 trillion”, whereas the cost of responding on the scale that “many suggest” would be $4 trillion, plus at least another $150 billion a year—so perhaps it isn’t worth it, and we should spend the money on other priorities?^N123

It sounds authoritative until you wonder what basis there is for choosing the time horizon (5 years? 100 years?) that you need for a tidy costing, why there is no sign of taking into account the large saving derived from improvements in energy efficiency, and why the estimate for the cost of climate change is so low; indeed, how can the prospect of runaway climate change be costed at all? It is necessary also to recognise that “other” uses of the money, such as providing clean drinking water, will become both impossible and pointless as global warming takes its expected course, unless a dramatic reduction in emissions is achieved in the near future. There is nothing there—no estimate, no investigation of the subject, no argument; and yet those hard-headed numbers have proved to be effective propaganda. One spoof number is worth 743 carefully-researched words.

Related entries:

Pascal’s Wager.