Philosophy of Science and 'Certainty'

pearson, hempel, goodman, kuhn, feyerabend

Can we have certainty in the statements we make about the natural world?

From the early part of the twentieth century to the publishing of Kuhn's The Structure of Scientific Revolutions the history and philosophy of science this term seems to be a movement from absolute certainty, to probable certainty, to relative certainty .

Absolute certainty seems to be best illustrated by Karl Pearson. He states that “there is no short cut to truth, no way to gain a knowledge of the universe except through the gateway of scientific method (20 Pearson).” Thus, for Pearson, science’s certainty is guaranteed by its unique method. The problem with assuming that science’s method (which is uniquely objective) guarantees its certainty, is in defining just what that method is.

Pearson describes scientific method as objective because its practitioners are unbiased by any social prejudices. They simply collect facts, without preconceived notions of what those facts may tell us. From these objectively collected facts we infer irrefutable theories.

There are obvious (and numerous) problems with this description of scientific method. Even ignoring the notion of the unbiased scientist (which has been shown to be patently false on a number of occasions...Lysenko and the Tuskegee Syphillis experiments being the most obvious examples...) there are still problems with the unbiased collection of facts. Karl Hempel lays out the problems with Pearson’s simplistic view of scientific method rather well. Since you cannot collect all the facts, you have to decide which facts are relevant to your particular purpose. Thus, you cannot collect facts without already having a hypothesis about what counts as relevant. And then there is always the problem of induction (how we get from empirical facts to general theories). Thus, neither fact collecting nor theory inference are objective, and cannot guarantee certainty.

So Hempel reformulates what scientific method is. He sees all the collection of facts and the induction of theories as preliminary, non-scientific events. The real ‘science’ does not begin until we have a testable rule. How we get this rule, be it from objectively collected facts, or the dreams of a madman, does not matter. The guarantor of scientific certainty is in the process of testing these rules, which is a process of refuting and confirming theories through a variety of tests, and accepting the one that results at the end. Nelson Goodman states that, though we can have a refuted theory, which we know is not certain, we can never have absolute certainty of any particular theory. All we can have is probable certainty. This is a result of the fact that we can never fully confirm a theory (because that would mean we had absolute knowledge with which to compare it with and say that it corresponded with) but we can have theories that are more or less highly confirmed.

There are, however, problems with the notion of confirmation. Most importantly, in order to confirm (or ‘probably’ confirm) a theory, we have to appeal to something external to that theory. For science, this is the external world. It seems to me that an appeal of this sort assumes that we are not limited by any particular worldview and have direct access to the real world. This seems to beg the question. If we are attempting to confirm a theory about the real world, we cannot simply look at the real world and say whether that theory measures up to it or not. If we could, then we would already have a comprehensive theory of the real world and wouldn’t have to bother confirming other ones! Thus, scientific certainty cannot be based on confirmation (or, for that matter, falsification), whether it is probabilistic or absolute.

The relativistic view of scientific certainty proposed by Thomas Kuhn and Paul Feyerabend seems (yet again) more coherent to me. They agree that scientific certainty is possible, but not about the real world. Science is certain only to itself. Within the particular paradigm/worldview/epistemological system of science, any given statement can be absolutely confirmed. We can determine with certainty the atomic weight of hydrogen within the practice of science. The problem lies when science tries to say that a particular battery of tests on a particular sample of gas says something about the entire universe over all eternity. For Kuhn and Feyerabend (and myself), the attempt to leap out of ones own view of the worldview and see the universe from a God’s eye view is impossible and unjustifiable.

The only reference I have handy is the Kuhn one (sorry):

Thomas Kuhn, The Structure of Scientific Revolutions (Chicago, University of Chicago Press, 1962) Third Edition: 1996.
The Goodman article I was thinking about is called "The New Riddle of Induction"
Hempel's book is called The Philosophy of Natural Science
For Feyerabend references see my node on Paul Feyerabend
Karl Pearson, The Grammar of Science, 1892. reference.

Other 'philosophy of science'-esque nodes:

Paul Feyerabend
Imre Lakatos
How Science Undergoes Changes of Theory
The Strong Programme
Thomas Kuhn
Normal Science
Logical Postivism
Philosophy of Science
Descriptive and Prescriptive Philosophy of Science
All Swans Are White