A very intelligent friend of mine once argued that modern scientists were too much like the religious faithful. They repeated, dogmatically, the things their forebears had determined, focusing too much on the provisionally known at the expense of direct response to observation of the world. This is a common argument, and one that has some intuitive pull. Scientists are meant to be skeptics, looking always at the evidence and never at their own predilections and biases, ideally. So if an established paradigm of science is actually a bias, a limitation on the objectivity of scientists, then it must be hindering the progress of the discipline.
In "Structure of Scientific Revolutions," Kuhn essentially argues the opposite: that paradigms are not only inevitable due to the nature of perception and investigation - they are in fact vital to the progressive nature of science. Paradigms are the shared assumptions and ways of looking at the evidence that allow efficient intra-disciplinary communication. More importantly, they are larger-scale versions of the hypotheses scientists depend on falsifying. Scientists must assert that the Earth is the center of the solar system and check the evidence against that assumption before making it clear that that claim is false.
To explain this point, Kuhn makes an analogy with biological evolution: a paradigm adapts to the shifting environment of the scientists who practice it. Scientists are selecting the fittest paradigm for future scientists to operate under. In order to discover the best adaptive strategy, an organism must put forth a variety of possible ways of living and reproducing. It is essential that the strategy be tested against the evidence, and that it eventually be replaced by a more-fit contender.
The interesting question this book raises (though it is only discussed in the postscript), which I assume is the reason it is studied in Intro Philosophy courses, is whether this understanding of science is relativistic. In the traditional understanding of science, new paradigms are adapted to solve problems and anomalies in the old paradigm, places where it failed to correctly model Reality. They are thus progressive, and through this adaptation science is supposed to move closer to a precise understanding of the Universe-as-it-really-is. But philosophers have long argued that there are too many barriers in the way for humans to discover things-in-themselves. The evidence is too much mediated by culture and biology, in ways that science can mitigate but never overcome.
Kuhn asserts that this does not necessarily mean that each paradigm is are no better than another, and that science is not progressive. He emphasizes that science should be seen as moving-from-poorer-explanations rather than moving-toward-perfect-explanations, but still believes there is some progress here, that modern science truly offers much better explanations of the data than previous ones. But Kuhn never tries to defend the idea that the idea-needs of modern scientists are based on any objective, absolute criteria and no simply on the whims of changing culture. I happen to believe in science the way Kuhn does, that we cannot know real Truth (and perhaps there is no such thing) but that science can still progress in measurable and objective ways. I just don't know if I could defend that claim against a real skeptic.
I picked up the book because I was frustrated with my education as a scientist. I thought that, at a liberal arts school, science education would be as much about history and philosophy of science as it was about learning the modern paradigm. However, the difference seems to be more in the way the paradigm is taught. I hoped Kuhn's book would give me more perspective in thinking *about* science, and it definitely accomplished that. It is a nice perspective on science's relationship to truth-seeking, and its development from amorphous explanations to precise predictions.
I found Kuhn's writing fairly impenetrable, and I would have had to spend a lot more time parsing out his specific usage of terms and following his thoughts more specifically to really get his philosophical argument into clarity. But the superficial understanding I took away satisfied my goals in reading the book.