This piece was originally delivered as a lecture by Dr. Madsen Pirie to students at the beginning of Freedom Week 2017.
David Hume had a problem with induction. Put starkly it is that it rests upon the shaky ground of an assumption that what happened yesterday will happen again tomorrow. Hume could not find a causal thread that linked previous events to future ones, and thought it ultimately depended on an act of faith, unsupported by evidence or reason, that linked future events to historic ones.
In the Twentieth Century Sir Karl Popper solved Hume’s problem of induction. Popper proposed that instead of using induction to develop theories, we use creative imagination to suggest them, and then test them to see which ones work in practice. Her called the process “conjecture and refutation,” claiming that instead of ‘inducing’ theories from past events, instead we conjecture what might be the case, and then test the conjectures to see if they can be refuted from practical observation.
Thus Hooke’s Law, for example, suggests that the extension of a spring is proportional to the force applied to it. That is the conjecture. We then apply weights to springs and measure the extension to see if it does indeed vary in proportion to the attached weight. If it does not, we discard the theory. The theories we retain are the ones that are supported by experiment; the ones we discard are those that do not.
Science proceeds by what I call a "selective death rate." When I used this term on a Radio 4 programme series about "Learning from Life and Death," the producer found the term "macabre," as he put it. Perhaps it is, but it simply means that we reject the theories that don't cut it. They die. The ones that pass experiments live on.
The upshot is that what we call our scientific knowledge is the collection of theories that have been tested, and have not so far been discarded. Note that they are tested in practice. It is their performance in observed tests that decides which ones live and which ones die.
Note also that the successful theories only live on until a better one comes along, one that can enable us to predict what we shall observe better than previous ones were able to do. Like ourselves, theories are mortal, and they live only for a time.
The market economy
There is a striking parallel between this account of scientific methodology and the operations of a free market economy. In a market economy people are free to introduce new products and processes. They are tested in the market to see if they appeal to consumers more than do existing products and processes. The ones that do so survive, while the ones that do not are counted out.
A market economy, like scientific method, operates through a selective death rate. Unsuccessful products and processes are eliminated, while the more successful ones survive. We look at the list of leading companies, and we find that most were not there twenty-five years ago. The names that seemed so dominant then are now distant memories, their places taken by names such as Apple, Google, Amazon and Facebook. Many of the products that were ubiquitous and dominant a quarter of a century ago are now regarded as anachronisms, to be regarded with amused wonderment when dug out of forgotten cupboards to be surveyed by today's children,
There are other important parallels between scientific method and market economies. Scientific discovery works faster in a society where people are free to investigate, to explore and to innovate. It depends upon freedom of information to spread new ideas and to report on the experiments that have tested them.
A market economy similarly makes faster progress if people are free to innovate and to introduce new products and processes without state or other interference or impediments. It, too, requires freedom of information so that knowledge of success can spread.
They have something else in common, too. Both are areas in which progress can be made. In both of them there is a goal or goals, so that attempts to reach towards these can be tested against each other to see which ones approach closer to it.
In science the aim is to extend our ability to predict what we shall observe, and theories are tested in experiments to see which ones do it better than their rivals. I part company with Popper at this point, because he thought that by proving things false we could approach closer to objective knowledge about the universe. I do not think we can do that, because we can no more prove something to be false than we can prove something to be true. We discard theories not because we know them to be false, but because they serve our purposes less well than the ones we retain. The aim is to predict what we shall observe, and we retain the theories that enable us to do that better than the ones we discard.
In a market economy, our aims include being able to better our lot, to make best use of scarce resources, to be able to satisfy more of our desires, and so on. We can test products and processes against each other to see which ones best enable us to achieve these things.
Thus progress is possible in both science and market economies. In science we can become able to predict more, and in a market economy we can become wealthier and satisfy more of our desires.
There is, of course, another area characterized by a selective death rate, and that is evolution. New mutations are tested by their ability to survive and reproduce in their environment. Those that do so live to breed and become the dominant new strain. The ones that do not are counted out.
I would draw your attention to two significant facts. One is that scientific discovery and a market economy both have the inspired minds of creative human beings behind them. People think up the new theories and the new products that have to be tested.
In evolution the mutations are random. This means that the changes in evolution are slower than those in science or economic activity. Innovation in biological evolution is blind, whereas in the other two it is inspired and directed.
The other significant fact is that we cannot speak of progress in evolution because there is no goal to work towards. There is only an environment that changes in ways that allow some mutations to prosper at different times if they are better equipped to meet the new conditions.
In summing up, I myself take the view that we humans try to improve our lot, or our performance, or our understanding, and that we do so by a method of inspired trial and error. We do it by introducing innovations and testing them in the real world. We retain the ones that achieve our aims better, and we discard the ones that do not. This is how we progress toward our goals.
I add in conclusion something about myself. I am optimistic about human creativity and ingenuity. By this method of inspired trial and error I think we can meet any challenge and solve any problem.