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The Validity of Scientific Method and Kuhn's 'Incommensurability'

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Humanity, for motivations which continue to be points of contention, has an insurmountable inclination towards scientific progress, whatever this may be. The scientific revolution in the 16th Century, commencing with the publication of Copernicus' (in)famous treatise on the motions of the planets served as a huge jump in the method of scientific thought, and the musings of such influential figures as Bacon on inductivism serve as an excellent indication of the colossal change of thought which occurred around this time. In spite of the relative continuity of scientific thought since then, ideas of quantum and theoretical physics (and notably cosmology) have served - again - to cause scientists to question the way in which they have thought. This entry attempts to present some commonly accepted resolutions to problems surrounding scientific thought, and propose ideas which solve the problems inherent in these, for better understanding of the field.

Science and the Philosopher

For scientists, this manner of advancement has unquestioningly been their preserve, and has been relatively tacitly taken to be, simply, 'the way in which things are done'. But the philosopher, as Wittgenstein famously said, '[showing] the fly the way out of the bottle', it seems, finds it in his or her job description to question those aspects of 'common sense' that are, perhaps, a little less than sensical, and so the questioning of the true validity or legitimacy of 'scientific progress' serves as a bone of contention among philosophers of science.

Science and Philosophy

Quite simply, one might say, dropping an idea simply because it seems wrong and starting afresh seems little more than instrumentalist1, and while the scientific revolution marked a large change of this sort, this is the way in which scientists function in everyday life, from the internal workings of amino acids in animals to the motion of fundamental particles in a particle accelerator. When a new idea comes along which better justifies (or explains) the way in which the world works, we leap upon it, either using it as a replacement for the ideas we (as hypothetical scientists) already had, or corroborating our existing ideas with new data and hypothesising a form of synthesis of previous theses.

In light of the fact that these scientifically invalidated ideas were at one point seen to have validity, and in some (supposedly objective) sense seen to be true, however, how can scientific progress be a coherent notion? For science to judge that an idea is invalid, it must look from the perspective of the new ideas, and in this sense, science is simply defined by the latest or best-accepted ideas. Even disregarding the relative subjectivity of science (in that there are always competing theses, and we have no real way of telling which will become generally scientifically accepted to the point at which they serve as an objective measure of other forms of science), this seems to be a fallacy: a simple self-perpetuating system. How, then, do we have any sort of scientific progress, given that our ideas simply seem to change amorphously, with no visible ascension to anything, towards which our hypothesising might be seen as progress?

Where Kuhn Fits Into It

For Kuhn, a figure from the 20th Century significant in the philosophy of science mostly as a result of his seminal work The Structure of Scientific Revolutions2, the question at stake here is simply summed up by one term, present in the title: 'incommensurability'. Kuhn's argument here - a riposte to those who argue that science is purely instrumental - is fundamentally summed up as follows: that there is no scientific statement which may claim to be objectively true, in light of two major facts.

Fundamentally, all observational data, according to Kuhn (and Feyerabend, a contemporary of Kuhn), is interpreted in light of scientific theorising, and so there is no way in which corroboration may be claimed which sufficiently justifies paradigms' states as objective truth. Secondly, he states that - further to scientific theories not being (properly) justified with relation to objective empirical evidence - scientific theories are in fact judged after having passed through the interests, biases, and sensibilities of the scientists involved, the overall picture here being one of relativism, and supremely sceptical relativism at that, the ultimate conclusion being one of empirical observation having little (if any) value.

Kuhn's incommensurability, then (a term, coincidentally, alighted upon by Feyerabend independently in order to describe the same phenomena), is simply a question of different ideas being incompatible. As Ladyman writes3:

Incommensurability is a term from mathematics which means 'lack of common measure'.

The Ladyman summary of this is curt, but thorough; he states that:

Kuhn likens a paradigm change to a 'gestalt switch' of the kind one experiences when alternately seeing the picture above as a duck and then a rabbit.

A Critique of Kuhn

It is to be noted that this is neither 'the truth', nor a commonly accepted opposition of Kuhn's ideas - simply another perspective, which makes sense to be presented in compliment to his ideas. In understanding philosophy, it almost always helps to have a dialectic of opposing ideas - indeed, this is how almost all of Plato's work is written (as dialogues).

This, however, incorporates an idea of the underlying truth being the same, the sense data which causes us to believe scientific theory X ultimately remaining the same. A given sense datum remains the same, the underlying picture, despite Kuhn's empirical relativism, being that of a world which is - if not inherently rational, this being another argument altogether - at least to some degree coherent. We are able to observe contiguity in the way in which things behave, this being the basis for inductivism. This, surely, at least serves to diminish the significance of Kuhn's argument, if not to any degree refute it. If we are able to at least identify patterns in the way in which the world operates, then this invalidates any conception that empirical observation is invalid, by nature of the fact that - before alighting upon a scientific theory - we are able to commonly agree on certain things.

Without agreeing on a common model of universal motion of planets (be it heliocentric or otherwise), we are able to acknowledge that, given a commonly agreed fixed scale (something so arbitrary that little consternation should be shed over the fact that people do not necessarily agree to, or in practice happen to, measure things in totally similar ways) X planet moves in Y plane of motion (or, more simply, moves through Z collection of points). There are commonalities in the universe, in other words, which we can agree on before trying to explain them.

Kuhn's invalidation of scientific terms, then, is surely also to be questioned: if we take it as read that there are commonalities in the universe, scientific terms may in fact be applied simply as descriptors of what events come to pass; whether or not we agree that the sun is the centre of the galaxy (or universe, in the case of recent cosmology), we may at least acknowledge the motion of the bodies in question, drawing us to a common conception of the notion of the word motion. This seems more than a little like the argument which states that we cannot make any meaningful statements about the world simply because our conception of language is universal (with relation to realism). Quite patently, we do not have the same words applying to precisely the same sets of sense data. However, the descriptors we have attached are sufficiently similar that we can make (relatively) meaningful statements about the world. Similarly, our common sets of scientific vocabulary are not exactly correspondent to each other (by nature of the fact that they evolve as new ideas come to fruition), but they are not sufficiently blurred as to become ambiguous to the point at which scientific hypothesising becomes immaterial and invalidated.

Kuhn, to the mind of the author, seems also to have missed one extremely important (and also extremely common-sensical) point. We assemble scientific theories by pattern abduction, fundamentally, and in doing so, we have the best possible explanation which, by a combination of empiricism and rationale, we may assemble. Science as an, ceteris paribus4, even playing field, is one in which any informed person by participate, and by nature of intellectual critique (much in the same manner as philosophy) travels in a direction steered by the work done on it by all concerned. Criticisms of a given theory in science (more definitely than in philosophical circles) may be seen to invalidate aspects of (or the whole of) that theory, and in doing so, science advances. Our conception of the way in which science 'is', then, is based on the degree to which we can criticise what we already know.

If, then, we come to the realisation that our system of belief is invalid and that another would be preferential - and as a consequence, alight on this belief - how is this deemed to be any degree nonsensical (the implication of a critical application of the question raised), and why is this statement valid? It is far preferential, one would assume, to advance in this manner (and thusly progress) than stick to an old and outdated mode of belief.

A Conclusion

While we may live happy in the knowledge that our scientific beliefs (if, indeed, we hold any) are the latest in a lineage of invalidated paradigms, this does not to any degree invalidate the scientific theory which we hold at the minute. A pertinent example is:

As personal computers have advanced, I have - over the course of the last 12 years - possessed somewhere close to 20 different computers, for better or worse. As technology has advanced, I have bought four computers new, in the knowledge that in a few years time, the computer in question would be (to most purposes) useless. (Many more, I have bought out of sheer interest, having an interest in old computers, both for the purposes of better understanding the newer, more complex machines which evolved from them, and simply out of a sense of interested nostalgia).

The computers, however, have not been diminished in any way by the fact that they were simply right for their given time, nor does this apply to science. At some point in the far future, we may alight upon a set of paradigms (or, indeed, a simple paradigm which describes everything) to adequately describe the world for as far into the future as it is possible to envisage. (Similarly, there will indubitably emerge a point sufficiently far in the future at which the consumer computer market will freeze, there being simply no need for more advanced hardware).

However, up until that point, what science the computer industry, and, indeed, the intellectual pursuit of philosophy provide are the best which they can do at the time, and the constant re-evaluation, re-statement, and redesigning of what we already know, have, and understand is neither a bad thing nor the gestalt paradigmatic shift which Kuhn seems to associate relativity with in an apathetic, cynical way: quite simply, there is logic in the way in which all three of these to some degree comparable fields advance, and, in being so, we cannot legitimately say that scientific progress does not make sense, even if we do not subscribe to any, or all, of its dogma.

Further Reading

Further reading pertinent to the subject may be found in the following books, which served to assist the author in his preparation of this entry. All of which explore the problem in more depth.

  • The Structure of Scientific Revolutions, T. S. Kuhn.
  • Understanding Philosophy of Science, James Ladyman.
  • Blackwell Companion to Philosophy, N. Bunnin and E.P. Tsui-James (ed).
  • Cambridge Dictionary of Philosophy, Robert Audi (ed).
  • Penguin Dictionary of Philosophy, Thomas Mautner (ed)
1Loosely, usage of an idea or philosophy because it works, rather than because it is genuinely valid.2'Considered one of "The Hundred Most Influential Books Since the Second World War"' as the back cover of the University of Chicago Press third edition states.3Understanding Philosophy of Science by James Ladyman4Ceteris paribus is Latin for 'all other things being equal'.

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