WHY DOES IT WORK?

The first is the already noted generality: The method remains valid for different countries and different energy use sectors.

The second is the test of prediction from only a short series of data:

For example, when only the data for the period 1900 to 1920 are taken, the "prediction" (tested against the know!, record) is quite good for the next 50 years: Even natural gas comes out with a fairly small error, though before 1920 its market share was only 2% or less, and though the tested prediction period included a depression and a world war.

The third is probably the most important: Each curve is uniquely determined by a mere two parameters: a single point (what fraction at what time) and the slope at that point (rate of increase at that time). For example, the time at which a source reaches a 5% share and the rate at which it is then growing will fix the rest of the curve; this mercilessly rules out any manipulation.

Give us the Club of Rome's doomsday program with its hundreds of parameters and a flowchart like the cobweb of a Washington bureaucracy, and by changing a few parameters, we will turn it into a prediction that the world stands on the threshold of a veritable Garden of Eden; but a two-parameter formula that agrees with 200 years of history gives manipulators no quarters.

Moreover, a quantitative relationship is, in itself, only a correlation (no matter whether statistical or rigid); it does not necessarily imply a cause-effect relationship. For example, the higher the toothpaste consumption in a country, the more automobile fatalities it suffers (compare, for example, the US and Luxemburg). But it is not a cause-effect relationship: You cannot prevent traffic accidents by banning toothpaste.

Similarly, though mathematically it is true that the rest of the oil curve is fixed by the oil share and its rate of growth in the early 1900's, it does not at all follow that if Capt. Lucas had searched for mushrooms in Montana rather than for oil in Texas, the history of oil use would have been different.