Saturday, January 26, 2008

The futility of technology forecasting

I have at last come across the source of a key insight about the futility of technological prediction, e.g. as practiced by Ofcom (and economists passim) when trying to establish the net present value of a long future stream of innovation. Simply put: if you could predict the future well enough for a technology prediction to be meaningful, you would know enough to already have the technology in hand, thus vitiating the prediction.

I’ve come across this trope in various places; I now believe the idea originated with Karl Popper. Charles Pigden, a Senior Lecturer in Philosophy at the University of Otago referred to it in a Philosopher’s Zone podcast about conspiracy theories. (It’s a great podcast, by the way.)

Popper outlines the argument in the preface to The Poverty of Historicism (available on Google Book Search) as part of a refutation of historicism. Popper contends that he had shown in a 1950 paper, “Indeterminism in Classical Physics and in Quantum Physics,” subsequently updated in a chapter on indeterminism which is part of the "Postscript: After Twenty Years" to his Logic of Scientific Discovery, that, for strictly logical reasons, it is impossible for us to predict the future course of history. He sums up the argument in five statements:

  1. The course of human history is strongly influenced by the growth of human knowledge.
  2. We cannot predict, by rational or scientific methods, the future growth of our scientific knowledge.
  3. We cannot, therefore, predict the future course of human history.
  4. This means that we must reject the possibility of a theoretic history; that is to say, of a historical science that would correspond to theoretical physics. There can be no scientific theory of historical development serving as a basis for historical prediction.
  5. The fundamental aim of historicism methods is therefore misconceived; and historicism collapses.
The key step is (2). Popper contends that it is self-evident that if there is such a thing as growing human knowledge, then we cannot anticipate today what we shall know only tomorrow. He provides a logical proof in the papers mentioned above; in short, it amounts to showing that no scientific predictor (human or machine) can possibly predict, by scientific methods, its own future results. Since this logical argument applies to a predictor of any complexity, including societi4s of predictors, it means that no society can scientifically predict its own future states of knowledge.

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