April 13, 2016

Uncertainty: ‘Whereof one cannot speak, thereof one must be silent’

Comment on Lars Syll on ‘Uncertainty — the crucial question’

Blog-Reference and Blog-Reference on Apr 15

Imagine somebody throwing three golf balls amidst a cyclone over his shoulder into a very large sandbox. Clearly, the three balls form a triangle but no one can predict its form and size. Yet, the mathematician can ‘predict’ with certainty that the sum of angles is 180 degrees (if the sandbox is euclidean).

Analogously, while the future is ‘unpredictable’ certain aspects may be ‘predictable’ with high precision. Science is about invariants, that is, properties or relationships which remain unchanged over time. A famous example is E=mc2 which predicts not a single historical event but something that is the case always and everywhere. This is the scientific meaning of prediction.

A scientist simply ignores phenomena like flying down feathers because he knows that their trajectories are uncertain and that he will not arrive at anything like the Law of Falling Bodies by observing thousands of down feathers. Because of this, a scientist does not waste much time with uncertainty. Not because he does not know that it is a property of the real world but because there is not more to say about it than: “The future is unpredictable” (Feynman).

From the acceptance of ‘Keynesian uncertainty’ three conclusions follow: (i) uncertainty does NOT exclude invariants (= economic laws), and (ii), history gives no clue about the future evolution of the economic system, and (iii), Wittgenstein’s time-saver applies, i.e. ‘Whereof one cannot speak, thereof one must be silent’.

So, uncertainty is NOT a worthwhile issue or a noteworthy discovery of Keynes, just the contrary, it is a truism since the invention of oracles. Science is about certainty.

Egmont Kakarot-Handtke