history and philosophy

This is truly one of the landmark works of 20th century philosophy of science. It is written by Thomas Kuhn, who was for decades a philosopher of science at MIT. His extensive background in physics gives him a unique perspective from which to author a book such as this.

The core thesis is that science can only make minimal progress without the existence of paradigms. Without a working model, science descends into mere arbitrary, usually aimless cataloging of data without any means to unify the data into a cohesive whole.

Over time, of course, there are paradigm shifts in which one model replaces another. It is this phenomenom that Kuhn traces; scientific revolutions. There is always much resistance to new theories / paradigms - especially by the older scientists in a field which may be impacted by the subject paradigm. Kuhn points out that very often it is the younger scientists who usually make the greatest contributions, for they are not "set in their ways." Human psychology enters into the equation more and more the older the scientist happens to be; his scientific upbringing may cause him to ignore or reject anything which challenges his neat & tidy view of the universe.

Contrary to popular belief, it is not the purpose of a paradigm to eradicate every single anomaly or instance of data which does not favor it. These idiosyncrasies of nature are to be worked out (or attempted to be worked out) by what Kuhn labels "normal science," which are the periods in between scientific revolutions.

What makes one working model more attractive than another is the way its answers to the "big general questions" of the particular field are superior to its rivals. Of course, how much slack a given paradigm should be given before it is discarded (due to contrary empirical facts) is not queried in detail by Kuhn. I suppose that the determination is always that such-and-such a model provides "the best answer available" to our considerations of nature.

Perhaps the most famous line appears on page 90: "Almost always the men who achieve these fundamental inventions of a new paradigm have been either very young or very new to the field whose paradigm they change." Kuhn's point, I believe, is correct. However, this line has been abused more than any other passage in the book. Minority groups with axes to grind have "translated" this statement as thus:

"BECAUSE our paradigm is not accepted by the scientific community, and BECAUSE we were not brought up in the same educational environment as they, THEREFORE our paradigm is only valid one - de capo. ANY resistance to our way of thinking about things only goes to show how legitimate paradigms are ignored and rejected by the established powers that be in the scientific community - just as Thomas Kuhn wrote."

It is non-sequiters such as these that led Kuhn to vehemently declare to the famous Princeton physicist Freeman Dyson that "I am NOT a Kuhnian!"

This book is highly recommended to philosophers, scientists and philosophers of science, as well persons who are curious about the idealogical engines which drive science. A fascinating inquiry into the nexus between human psychology and scientific thought.

Kuhn's work in The Structure of Scientific Revolutions basically introduced the history of science to philosophers of science. Slowly but surely, they came to see the philosophy of science as something more than applied formal logic. But as someone who doesn't work in philosophy of science, I find this book fascinating for other reasons. The most important reason is that this book, like much good philosophy of science, works for me as a sort of applied epistemology since Kuhn takes up abstract philosophical arguments and applies them to particular episodes in the history of science.

Of course, as most everyone knows, Kuhn's account of the history of the sciences revolves around the notion of a scientific paradigm. A paradigm, in the most important sense, is a set of standards, practices, and theories shared by a group of scientists. So a paradigm includes all the following things: the central theories of the relevant science, important experimental results and techniques, guidelines concerning which problems are and are not important, standards of evidence against which theories are to be judged, etc. Through the reading of textbooks, studying with proponents of the paradigm, and doing labwork of certain sorts, individual scientists come to accept the elements of the paradigm.

When there is a regnant paradigm in a particular science, what Kuhn calls 'normal science' occurs. Normal science primarily involves puzzle-solving, which is a matter of attempting to solve the problems the current paradigm tells us are important and solving them in ways consistent with the methods and theories of that paradigm. Normal science is not a wholly stable enterprise, though, for it is always the case that anomalies, problems the paradigm seems unable to solve, develop as the paradigm is applied to new phenomena. Isolated anomalies are usually ignored, on the assumption that further development of the paradigm will lead to their solution. But not all are solved even in the long run, and eventually there are enough of them that working scientists begin to take notice. This is when the science enters a crisis period, when the once-obvious truth of regnant paradigm begins to seem less obvious to many scientists. Now scientists begin to propose new paradigms, and some win converts. When one of the new paradigms proves able to solve many of the glaring anomalies that plagued the previous one, most scientists will switch over to the new paradigm and those who do not will eventually die off. Following this revolutionary paradigm switch, there is another period of normal science as working scientists begin applying the new paradigm. This process, according to Kuhn, is probably an endless one.

And it is the details of Kuhn's account of paradigm change that appears to result in certain problems for the objectivity of science. In particular, the nature of scientific revolutions seems to preclude a gradual progress of the sciences towards the truth about the world; or, at least, it does not allow us to guarantee that such progress will occur. Why? Because it seems paradigm change cannot be based on an objective consideration of the evidence for and against particular paradigms.

The central worry about the objectivity of science arises from what Kuhn calls the 'incommensurability' of different paradigms. There are at least two distinct worries here. First, there is what we might call 'standard incommensurability'. When the accepted paradigms change, the accepted standards of a good scientific theory change--different experiments are conducted, different evidence is taken to be conclusive, and old problems are ignored. So accepting up a new paradigm means you're bound to see that paradigm as better justified than its competitors; indeed, it means you're bound to have real trouble seeing what competitors take to be evidence for their preferred paradigms.

But, one might wonder, isn't the objectivity of science assured through reliance on observations that can be shared by different scientists and on experiments that can be repeated? Not so, Kuhn argues, because the theory-ladenness of observation undermines the possibility of such a theory-neutral set of empirical data. We don't test theories against raw observations; we test them against observations that are interpreted in light of the theories we hold. What theory you hold partially determines what you see, and so it partially determines what you take to be observational evidence. So proponents of different paradigms will see different things in the same experiments and observations, and thus there isn't any theory-neutral body of empirical evidence to which we can appeal in determining which of the competing paradigms should be adopted.

There is a second form of incommensurability, viz. meaning incommensurability, and it leads to similar problems. Kuhn accepts a holistic semantics of scientific terms according to which the terms used by scientists acquire their meaning from the network of theory in which they are used. The meaning of a scientific terms--like, say, 'gravity'--is determined by the paradigm in which it is being used. Consequently, when paradigms change, so do the meanings of the terms employed by scientists. So, for instance, the word 'gravity' has a different meaning in Newtonian physics than it has in current relativity theory. This has a significant result for the nature of debate between proponents of different paradigms: namely, that proponents of different paradigms are talking past one another. There is a misleading appearance of agreement and disagreement here, but proponents of different theories really can't argue with one another about the same phenomena since their words have different meanings.

The consequences of these different forms of incommensurability can seem pretty radical. First, standard incommensurability seems to show that paradigm change cannot be based on a consideration of evidence; and second, meaning incommensurability seems to show that a proponent of one paradigm cannot even understand the theories involved in another paradigm. The process of paradigm change, then, comes to seem necessarily non-rational. Scientists come to hold the paradigms they do for psychological or sociological reasons, and not because of a careful consideration of the evidence for and against the various available paradigms. And if this is the case, it's not at all clear why we should think that the history of science involves a trend towards a discovery of the truth about the nature of the world around us.

The complete title of this review is "Philosophic common sense applied to Science Evolution of Thought". Basically the central thesis of Kuhn was that science evolves through paradigm shifts, and of course he conceives science as a compound of theories and laws based on the most agreeable paradigms of the epoch. I found this book refreshing and interesting from at least two perspectives, filosofically and historically. Also this book is read as a compendium of consecutive works that altogether make a coherent thesis, so it's easy reading it. Finally, Kuhn's style is very friendly and personal, so you really feel he is urging you to follow him in all his arguments. Reading this book was a great experience for me, and I highly recommend it.