Kuhn, Revolutionary Science

• Crisis
  • Accumulation of anomalies
  • Loss of faith in the paradigm
  • Rival Theories
  • Other Factors
    • Social and political upheaval
    • Institutional changes
• Revolution
  • What distinguishes revolutionary political change from non-revolutionary change? In revolutionary change, old mechanisms, institutions, and procedures get replaced by new ones in a setting in which there are no stable mechanisms, institutions, or procedures to supervise, adjudicate, or control the change. There is no standard or decision procedure. Similarly, Kuhn says, in a scientific revolution, there are no standards or procedures for deciding which paradigm is better. One doesn't decide on clear rational grounds to switch paradigms. It is more like "a religious conversion."
    • Many have taken Kuhn to be claiming that the change is wholly irrational, and concluded that he is a relativist about truth: that is, there is no fact of the matter about which is right, truth is only within, relative to, a paradigm. Kuhn did not claim that there can't be good reason for preferring one paradigm over another. He "only" claimed that there is no method for deciding between paradigms, and that one cannot correctly assess a new paradigm from within an old one. (More generally, no paradigm can be correctly assessed by assessing from the standpoint of another paradigm.)
• Incommensurability
  

Incommensurability literally just means not measurable with a common unit. Kuhn said that different paradigms are incommensurable. He did not say that they are incomparable, only that they can't be judged by the same standards.

• • Incommensurability of observation
  • Incommensurability of method
  • Incommensurability of standards
• The Replacement of One Paradigm by Another is Not Cumulative
• Theory Ladenness of Observation
  

According to Kuhnians: There is no such thing as a straight observation, independent of our theories, beliefs, paradigms. The idea of empirical evidence that is neutral between theories and can be used to decide between them is a myth.

The obvious conclusion from all of this is that scientific revolutions, paradigm shifts, are irrational in the precise sense that they are not made and cannot be evaluated on the basis of reasons. If that is true, we have no reason to trust the pronouncements of science.

Kuhn did not believe that. What he believed is that there is no single overarching system of rational scientific principles adequate to decide between paradigms. There are some principles that probably always apply:

• A theory that explains more evidence than another is better.
• If two theories explain the same evidence equally well, the simpler is better.
• The more surprising predictions a theory has made, the better.

Kuhn's point is that that is not enough to decide between paradigms when there is disagreement about what constitutes good evidence, what kind of simplicity is important, and so on.

Good judgement and taste is required to decide. It is often the case that it is not clear which paradigm is better for a long time.

One important criterion is that the paradigm that supports more successful normal science is better.

-- ShaughanLavine - 03 Oct 2005 - 24 Sep 2007