Jul 07 2011

The logic of science-2: Determining what is true

(For previous posts in this series, see here.)

An important question in any area of knowledge is being able to identify what is true and what is false. The search for what is true and the ability to know when we have discovered truth is, after all, the Holy Grail of epistemology, because we believe that those things that are true are of lasting value while false statements are ephemeral, usually a waste of time and at worst harmful and dangerous.

Aristotle tried to make a clear distinction between those things that we feel we know for certain and are thus unchanging, and those things that are subject to change. The two categories were variously distinguished as knowledge versus opinion, reality versus appearance, or truth versus error. Aristotle made the crucial identification that true knowledge consisted of scientific knowledge, and his close association of scientific knowledge with truth has persisted through the ages. It also made the ability to distinguish between scientific knowledge and other forms of knowledge, now known as the demarcation problem, into an important question since this presumably also demarcates truth from error. (This brief summary of this history is taken from the essay The Demise of the Demarcation Problem by Larry Laudan which should be referred to for a fuller treatment.)

Aristotle said that scientific knowledge was based on foundations that were certain and thus was infallible. Since he identified scientific knowledge with true knowledge, it followed that scientific knowledge had to be unchanging because how could truth ever become false?

The second characteristic of scientific (and hence true) knowledge was that it should consist of not just ‘know-how’ but also of ‘know-why’. ‘Know-how’ knowledge was considered to be the domain of craftsmen and engineers. Such people can (and do) successfully build boats, bridges, houses, and all manner of valuable and important things without needing an understanding of the underlying theoretical principles on which they work. The electrician I call to identify and fix problems in my house has plenty of know-how and does his work quickly and efficiently without having to understand, or even know about, Maxwell’s laws of electrodynamics (the know-why), whereas any scientist would claim that the latter was essential for really understanding the nature of electricity.

It is for this reason that Ptolemaic and early Copernican astronomy were not considered scientific during their time even though they made highly accurate predictions of planetary motions. Their work was not based on an understanding of the laws that governed the motion of objects but on purely empirical correlations, and thus lacked ‘know-why’. If, for example, a new planet were to have been discovered, existing knowledge would not have been of much help to them in predicting its motion. Hence astronomy was considered to be merely know-how and astronomers to be a species of craftsmen.

The arrival of Isaac Newton and his laws of motion provided the underlying principles that governed the motion of planets. These laws not only explained the existing extensive body of data on planetary motions, they would also be able to predict the motion of any newly discovered planet and even led to the prediction of the existence of an actual new planet (Pluto Neptune) and where it would be located. Newton’s theories provided the ‘know-why’ that shifted astronomy into the realm of science.

It was thought that it was this know-why element that made us confident that scientific knowledge was true and based on certain foundations. After all, even if a boat builder finds that all the wood he has encountered floats in water, this does not mean that the proposition that all wood will always float is necessarily true since it is conceivable that some new wood might turn up that sinks. But the scientific principle that all objects with a lower density than water will float while those with a higher density will sink seems to be on a much firmer footing since that knowledge penetrates to the core of the phenomenon of sinking and floating and gets at its root cause. It seems to have certain foundations.

As a consequence of the appreciation that ‘know-why’ knowledge has greater value, science now largely deals with abstract laws, principles, causes, and logical arguments. Empirical data is still essential, of course, but mainly as a means of testing and validating those ideas. Many of these basic ideas are somewhat removed from direct empirical test and thus determining if they are true requires considerably more effort. For example, I can easily determine if the pen lying on my desk will float or sink in water by just dropping it in a bucket. But establishing the truth of a scientific proposition, say about the role that relative densities play in sinking and floating, is not that easy.

So given the primacy of scientific principles and laws in epistemology, and since the discovery of eternal truths is to be always preferred over falsehood, an elaborate structure has grown around the whole exercise of how to establish the truth and falsity of scientific propositions, often requiring the construction of expensive and specialized equipment to determine the empirical facts relating to those propositions, and extensive long-term study of esoteric subjects to relate the propositions to the data.

Next in the series: The demise of infallibility

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