Does science consist in the progressive development of objective truth? Contrast the views of Kuhn with one other writer on this topic. The philosopher and historian of science Thomas Kuhn introduced the term paradigm as a key part of what he called "normal science": In normal (that is non revolutionary) periods in a science, there is a consensus across the relevant scientific community about the theoretical and methodological rules to be followed. (Marshall 1998). Paradigms tend to shift over time as new scientific discoveries are made, and anomalies or observations that conflict with the current paradigm begin to accumulate.

Eventually this leads to a scientific revolution. There is a shift from one paradigm to another and a new period of normal science begins. So, what seems to be scientifically relevant at one time may not be so in years to come. An example of a paradigm shift would be when it was discovered that Earth was not the centre of the universe and that the sun did not revolve around the earth. This was a widely held belief up until, and even after there was proof to show that these beliefs were held falsely.

Kuhn argued that the way scientists choose what conceptual and theoretical framework (what 'paradigm') they should apply in framing their scientific questions and in seeking to resolve scientific puzzles is necessarily heavily influenced by subjective factors, including prevailing social norms and conventions. This implies that scientific theories are subjective and therefore so is the "truth" they aim to show. Kuhn argued that an old scientific paradigm is occasionally displaced by a new one and that in some senses the scientist finds himself working in a "different world." For Kuhn, what counts as true in one paradigm is different from what counts as true in a different paradigm. Another way of putting this is that truth does not survive a scientific revolution.

This means that Kuhn can be seen as a relativist as his argument suggests that there is no external reality by which we are able to measure the truth of scientific theories and that the truth changes with each new paradigm. Thomas Kuhn observed that science, as it's actually practiced, isn't the logical and cumulative building up of a true picture of the world that it was generally believed to be. He showed that there is no fixed, defined criterion for deciding between competing scientific paradigms. This was taken by many scientists and many nihilists to mean that any theory was as good as any other For Kuhn, the selection of scientific theories is driven by problem solving. When, during a period of normal science, some problems cannot be solved using existing theories, then new ideas proliferate, and the ideas that survive are those that do best at solving these problems. But nothing made it inevitable that science would evolve toward anything objectively better.

Kuhn recognizes that Maxwell's and Einstein's theories are better than those that preceded them, but when new problems arise they will be replaced by new theories that are better at solving those problems, with no overall improvement. Kuhn infers that there truly is no ultimate objective reality at all; 'truth' is just what the scientists tell us it is at some given point in time. This, of course, strikes at the heart of the traditional view of science which takes for granted that objective reality and ultimate truth exist and that scientists are gradually approaching it through cumulative revolutionary progress. Kuhn agrees that science evolves, but he rejects the idea that the evolution of science is goal-directed. Kuhn's views can be contrasted with realist views that claim that competing theories or successive theories are often about the same things. According to realists scientists attempt to provide theories which better explain the behaviour of the same kinds of things already referred to by earlier theories.

Karl Popper can be viewed as a realist as he believed that new scientific theories "must always be able to fully explain the success of its predecessor" (rationality of scientific revolutions). Where the old theories were successful the new ones must yield results that are at least as successful if not more so. This is how Popper determines scientific progress, by judging the quality of a theory compared with its predecessor. New theories explain the same ideas as the old ones and progress when they also explain a wider range of problems. Popper disagreed with the idea of theories being proven or verified over time. He ague d that no matter how many times a theory is seen to be correct we can never be sure that it is the truth.

Instead he argued that the more a theory survives attempts to refute or falsify it, the more highly corroborated it becomes. It is thus increasingly reliable as a guide to predicting future events, and one can ever more confidently hope that, to some degree, it reflects the regularities actually out there. But there is no guarantee that it is a complete and true reflection. While the falsifiability criterion appears to reorient science away from the commonly-held idea that it is concerned to establish objective truths, Popper recognises that observations are themselves theory dependent and that it is always possible to refuse to accept the validity of an observation. For Popper theories are not matched against observations as if the world could be known a priori irrespective of any theories people have about the world. Rather theories are matched against each other and compared to measure progress.

Popper stresses there are no 'pure' facts available; all observation-statements are theory-laden and influenced by our background assumptions, and are as much a function of purely subjective factors (interests, expectations, wishes, etc. ) as they are a function of what is objectively real. Scientific theories, for him, are not inductively inferred from experience, nor is scientific experimentation carried out with a view to verifying or finally establishing the truth of theories; rather, all knowledge is provisional, conjectural, hypothetical - we can never finally prove our scientific theories, we can merely conclusively refute them; hence at any given time we have to choose between the potentially infinite number of theories which will explain the set of phenomena under investigation. Faced with this choice, we can only eliminate those theories which are demonstrably false, and rationally choose between the remaining, un falsified theories. According to Popper, the growth of human knowledge closely resembles the process of natural selection. 'Our knowledge consists, at every moment, of those hypotheses which have shown their (comparative) fitness by surviving so far in the struggle for existence" (Popper 1979, 261).' Thomas Kuhn argued that our ideas of scientific truth can change with each new paradigm which implies that there is no objective scientific truth at all, that all truth is necessarily subjective and therefore that any one scientist's theory is pretty much as good as any other's.

Kuhn himself didn't agree with that and tried to point out that this is not at all what he meant to say, and that scientific truths themselves are objective (not subjective), and truth itself is not relative -- he clarified that he simply meant that scientists are necessarily influenced by subjective factors, even in the choosing of what kind of conceptual framework and method they use to try to get at the truth of things. Kuhn is quite neutral on whether or not there is an objective truth or reality. His main point is that scientific progress is a continuing refinement of our ideas about what might be the case. He says there's no single criterion for selecting one theory over another, not even success at predicting phenomena. The only judge is the consensus of the scientific community, and that clearly changes so it can't be used in advance to decide one theory over another. Popper also argued that we can never be sure that our theories will never be falsified and so all knowledge or truth is provisional and can change.

It seems therefore that although Popper seems to follow a realist account of scientific progress and Kuhn a relativist one, that actually they both believed that there is progress in science but that we could not know if we were progressing towards an objective truth... Eklund, Robert, Jr. and Robert F. Hebert.

A History of Economic Theory and Method. Fourth edition. New York: The McGraw-Hill Companies, Inc. Kuhn, Thomas S. The Structure of Scientific Revolutions. Second edition.

Chicago: The University of Chicago Press, 1970. Popper, Karl R. The Logic of Scientific Discovery. New York: Basic Books, Inc. , 1959.