Lifespan does not measure ageing

The Gompertz equation, which describes the increase of mortality over time, is often used to measure the rate of the ageing process. However, a recent article argued that it is incorrect to use the function for this purpose and that its use should therefore be discouraged (Driver 2001). I believe that this conclusion is based on misunderstandings and that the Gompertz function (if used appropriately) is actually well suited to measure the ageing rate. Here I will solve the `paradox' posed by the author and argue that it is actually lifespan that is inadequate to measure ageing and not the Gompertz function.