Monday, October 14, 2013

The Next Time Someone Tells You Economics is a Science Remind Them of Mendeleev

From the Royal Society of Chemistry:
What is a mark of a great scientist? Good scientists discover new information and make sense of it, linking it to other data. They may go further by giving an explanation of this linked data which, maybe not immediately, other scientists accept as a correct explanation. However the outstanding scientist goes further in predicting consequences of his ideas which can be tested. This boldness identifies the great scientist if the predictions are later found to be accurate. One such person was Russian chemist Dmitri Mendeleev.....
If an economist can't make falsifiable predictions then what he's doing is something between religion and mental masturbation. From the ridiculous to the sublime, back to the RSC:

....Correct predictions

The greatness of Mendeleev was that not only did he leave spaces for elements that were not yet discovered but he predicted properties of five of these elements and their compounds. How foolish he would have seemed if these predictions had been incorrect but fortunately for him three of these missing elements were discovered by others within 15 years (ie within his lifetime). The first of these Mendeleev had called eka-aluminium because it was the one after aluminium (eka = 1 in Sanskrit) and was identified in Paris (1875) by Paul Emile Lecoq de Boisbaudran who named it gallium after the Latin name for France. Mendeleev was ecstatic when he heard of its properties which nearly matched his eka-aluminium. However de Boisbaudran's value for gallium's density (4.9 g/cm3) differed from Mendeleev's prediction. Mendeleev told the Frenchman, who re-measured the density to find Mendeleev was right! It is interesting to speculate whether de Boisbaudran was pleased or irritated by this. The table compares Mendeleev's predictions with de Boisbaudran's discovery.

Eka-aluminium (Ea)
Gallium (Ga)
Atomic weight
About 68
69.72
Density of solid
6.0 g/cm3
5.9 g/cm3
Melting point
low
29.78oC
Valency
3
3
Method of discovery
Probably from its spectrum
Spectroscopically
Oxide
Formula Ea2O3, density 5.5 g/cm3. Soluble in both acids and alkalis.
Formula Ga2O3, density 5.88 g/cm3. Soluble in both acids and alkalis.
Within the next ten years Swede Lars Nilson (1879) identified scandium, predicted by Mendeleev as eka-boron and German Clemens Winkler (1886) discovered germanium which he realised was Mendeleev's eka-silicon. These discoveries established the acceptance of the Russian's table, although two other elements whose properties were predicted were not discovered for 50 years....
Here's more on one of the predictions.

Two other points to consider:
1) The mere fact that economists use the tools of science (Maths) to do their work no more makes economics a science than bid and ask spreads make carbon trading market based.

2) Something all model makers and model users should keep in mind: "The map is not the territory" and  "All models are wrong, but some are useful".

The quotes are from:
-Alfred Korzybski
"A Non-Aristotelian System and its Necessity for Rigour in Mathematics and Physics" 
presented before the American Mathematical Society December 28, 1931
and
-George E.P. Box
Section heading, page 2 of Box's paper, "Robustness in the Strategy of Scientific Model Building"
(May 1979)
respectively.