This is the second entry on Thomas Kuhn, the first is Thomas Kuhn: Objectivity, Value Judgment and Theory Choice.
In the previous entry, we discussed the notion of scientific revolutions and how Kuhn proposed they came about. Science didn't progress smoothly with new facts adding onto or improving older ones, but rather science moved in revolutions where paradigm shifts created a new way to look at science and the world. These shifts were not the act of Truth-progression, but scientists making personal judgments and justifications as to which theory to support. Here we will discuss in greater detail this last part, the justifications of the scientist deciding between competing theories.
- Now, as stated in the last entry, Kuhn is trying to dismantle the belief that his proposal for scientific revolutions includes a type of "mob psychology" on the part of scientists. That is, whatever seems hip at the time for a scientist to believe is what he/she will believe and study/teach. If that was the case, they would be no better than sociologists.
Unlike a set of commandments that tell you exactly what to do, what decisions are right or wrong, Kuhn stated that there was no single rule set for determining support for competing theories.
"In the absence of criteria able to dictate the choice of the individual, I argued, we do well to trust the collective judgment of scientists trained in this way. 'What better criterion could there be ' I asked rhetorically, 'than the decision of the scientific group?'"
This may seem like a nice compliment to scientists - that they are most qualified to determine which theories to be supported. But quickly the mob turned against him, with scimitars, for this undermined what many scientists believed about their practice. If the worth of competing theories is only based on the group decision of qualified scientists, is it not more True than before? Many scientists surely thought they were discovering new Truths about the world, and that they chose Einsteinian physics over Newtonian physics because Einstein was Right and Newton was Wrong.
- This opens up a whole slew of questions about how these decisions are made, and thus about how science progresses: Who is actually a scientist? Why does science work so well if its just people deciding whats best? How does a scientist decide which theory is good and which isn't?
-It is the third query that we will address now. Kuhn provides 5 principle characteristics of a good scientific theory, not exhaustive characteristics, but the main ones.
1. Accuracy - "within its domain, that is, consequences deducible from a theory should be in demonstrated agreement."
2. Consistency - "not only internally or with itself, but also with other currently accepted theories applicable to related aspects of nature."
3. Broad Scope - "a theories consequences should extend far beyond the particular observations, laws or subtheories it was initially designed to explain."
4. Simplicity - "bringing order to phenomena that in its absence would be individually isolated, and, as a set, confused."
5. Fruitfulness - "discloses(s) new phenomena or previously unnoted relationships among those already known."
Scientists would've been just fine with criterion 1 as the sole one. Many want to get the right answer, turn around and smile a delightful smile. Copernicus was just more accurate than Ptolemy, they will say. HE WAS RIGHT!!, they will scream. The earth does move around the sun, they will haughtily profess.
- Now, the key to all of this is Justification. How do you justify who you believe, at the time, between Copernicus and Ptolemy. Because we must note that had it not been for Copernican supporters at his time, he might have faded into oblivion, and who knows, maybe we'd still be the masters of the Universe!!
"Copernicus's system, for example, was not more accurate than Ptolemy's until drastically revised by Kepler more than sixty years after Copernicus's death...The oxygen theory, for example was universally acknowledged to account for observed weight relations in chemical reactions, something the phlogiston theory had previously scarcely attempted to do. But the phlogiston theory, unlike its rival, could account for the metals' being much more alike than the ores from which they were formed. One theory thus matched experience better in one area, the other in another. To choose between them on the basis of accuracy, a scientist would need to decide the area in which accuracy was more significant."
But the Phlogiston Theory was wrong!! And Oxygen Theory Right!!!
- Let's not forget that Kuhn is here describing how scientists, at the time, come to support a certain theory over another. And at the time it is not so obvious. They have to individually make a choice - am I a Copernican or a Ptolemian? am I a Phlogistonian or an Oxygenationian? That choice will set the stage for further supporters to work within the, say Copernican, framework and discover new insights into a heliocentric universe. And had they decided on Ptolemy, they would be searching for and assigning evidence to the geocentric theory.
-Kuhn proposes that simplicity not accuracy was the main determining characteristic that made Copernican theory better than Ptolemian. "But that sense of simplicity was not the only one available, nor even the one most natural to professional astronomers, men whose task was the actual computation of planetary position."
Much like how the Bachelor has to decide which characteristic is most important to him - T and A, great hair, bubbly personality, etc., because it is not logically obvious which one is the correct choice. And what if I think Julie's T and A is the best and you think Laura's is?
"When scientists must choose between competing theories, two men fully committed to the same list of criteria for choice may nevertheless reach different conclusions. Perhaps they interpret simplicity differently or have different convictions about the range of fields within which the consistency criterion must be met."
- The fundamental point is that there are different characteristics of a good theory and the justification for choosing one theory over another is not always housed in logical accuracy.
Next Up: Kuhn: Values and Algorithms





























































