Kuhn - Revolutionary Science

Revolutionary Science

Overview

  • Theory Choice: How scientists choose between competing theories.
  • Normal Science: Scientific work done within an established framework or paradigm.
  • Revolutionary Science: A period of scientific upheaval where existing paradigms are challenged and replaced.
  • Crisis: A period where anomalies and inconsistencies within the existing paradigm become overwhelming.

Plan

  • What is a scientific revolution?
  • Incommensurability: The idea that different paradigms are not easily comparable.
    • Of standards and values.
    • Of meanings and observations.
  • Is this relativism? Does Kuhn's view lead to relativism about scientific truth?

Revolutions

  • Cause:
    • Growing unrest within the scientific community due to accumulating anomalies.
    • Polarization among scientists.
  • Rules:
    • During a revolution, normal rules and methods of science may not apply.
    • "Anything goes" - existing norms are questioned.
  • Resolution:
    • Not purely political; resolution involves mass persuasion.

Revolutionary Science

  • Definition: Revolutionary science occurs when there is more than one paradigm competing for dominance in a scientific community.
  • How do we choose?
    • Normal scientific methods don’t apply during revolutionary science.
    • Each camp often makes circular arguments to support its paradigm.
    • Ultimately, paradigm choice becomes a matter of mass persuasion.

How Revolutions Come About

  1. Normal Science: Leads to the accumulation of important anomalies that the existing paradigm cannot explain.
  2. Crisis:
    • Occurs when the reigning paradigm is questioned due to these anomalies.
    • The crisis may be resolved by normal scientific methods within the existing paradigm.
    • A rival paradigm emerges as an alternative explanation.
  3. Revolutionary Science Phase: If a rival paradigm emerges, the scientific community enters a phase of revolutionary science.
  4. New Paradigm Established: Eventually, a new paradigm gains acceptance and becomes the new framework for normal science.

Normal Scientific Methods

  • Why can’t we apply normal scientific methods during a period of revolutionary science?
    • Analogy: Why can’t we vote to decide between democracy and dictatorship?
    • The paradigm itself defines what constitutes normal science.
  • Example:
    • Hnormal: The hypothesis that there is a planet between Mercury and the Sun (explained within the existing paradigm).
    • Hrevolutionary: Einstein’s theory of relativity (a new paradigm).

Circular Arguments

*What’s a circular argument?

  1. The Bible is the true word of God.
  2. The Bible says God exists.
  3. Therefore, God exists.

*What’s Wrong with them?

*How can we argue for a new paradigm?

  1. Heliocentrism gives a more elegant picture of the heavens.
  2. In astronomy, the most elegant theory is best.
  3. Therefore, heliocentrism is the best theory.

How Revolutions End

  • How do we decide between paradigms?
    • Not by using normal science methods, as these are defined by the paradigm itself.
  • How do political systems get established?
    • Mass persuasion is crucial.
    • It’s not a fully rational process.
    • Social and political factors are relevant in the acceptance of a new paradigm.

Example: The Copernican Revolution

  • Myth: Copernicus discovered that the earth revolves around the sun.
  • Kuhn's View: Copernicus inaugurated a period of revolutionary science by proposing an alternative paradigm.
    • In response to important anomalies in the existing geocentric model.
    • Not following the established rules of normal science.
    • Could only offer circular arguments from within his heliocentric perspective.
    • Ultimately, despite resistance, people were converted to the heliocentric view.

Incommensurability

  • Definition: Rival paradigms are incommensurable, meaning they are "not of equal measure" and cannot be directly compared.
  • How are paradigms incommensurable?
    • Disagreement about standards and values.
    • Disagreement about meanings and observations.

Incommensurability of Standards and Values

  • Paradigms disagree about fundamental aspects of scientific inquiry:
    • What questions are worth asking?
    • What counts as an acceptable answer?
    • What unanswered questions are considered problematic and which can be ignored?
    • What are the most important features of a scientific theory?

Example: Ptolemaic vs. Copernican Astronomy

  • Geocentric (Ptolemaic):
    • Explains why we don’t feel like we’re moving.
    • Explains why things fall straight down.
    • Maintains the importance of Earth as the home of humans.
    • Provides a place for heaven.
  • Heliocentric (Copernican):
    • Explains why some planets always appear near the sun.
    • Offers a simple and elegant picture of the universe.
    • Makes certain calculations easier.
    • Allows for an infinite universe.

Example: Newtonian Gravitation

  • Why do things fall?
    • The force of gravity.
  • What is the force of gravity?
    • Newton's Statement: "I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction."

Example: Newtonian Gravitation (Continued)

  • If Newton can’t give a mechanism for gravity, has he explained why things fall?
    • Newtonians: Yes, the math works; the equations accurately predict gravitational effects.
    • Mechanists (Descartes): No, nature works like a machine, so you have to explain things in terms of direct contact between bodies. Descartes proposed that the universe is full of particles in contact, creating vortexes.

Value Incommensurability

  • Can you think of a case where there is a fundamental difference in values or standards?
    • Values: What questions are considered important to address.
    • Standards: What counts as a legitimate question and/or answer.
  • How can we resolve disagreements over values/standards?
  • Does this make science a matter of "mob psychology"?

Crucial Experiments

  • Optics Example:
    1. Newton: Light consists of particles.
    2. Fresnel: Light consists of waves.
  • Predictions:
    1. Light moves faster in water than in air (particle theory).
    2. Light moves slower in water than in air (wave theory).
  • Observation:
    • The Fizeau–Foucault apparatus (1850) refuted the first prediction and confirmed the second, supporting the wave theory: Fizeau–Foucault apparatus (1850)  ⟹  Light moves slower in water than air\text{Fizeau–Foucault apparatus (1850)} \implies \text{Light moves slower in water than air}

Meanings and Observations

  • Meaning Holism:
    • The meaning of a term depends on all the other meanings it connects to within a paradigm.
    • "Is light a particle?"
    • QED (Quantum Electrodynamics): A photon is a particle of light, but fundamentally an excitation of a quantum field.
  • Meaning Incommensurability: Rival paradigms may be "talking past each other" because their terms have different meanings within their respective frameworks.

Incommensurability of Meaning

  • Different paradigms may categorize the same object differently.
  • Paradigm 1: The moon is a satellite.
  • Paradigm 2: The moon is a planet.

Meanings and Observations

  • Theory-Ladenness of Observation: What we observe can depend on one’s paradigm; our observations are shaped by our beliefs.
  • Can you observe a sunset?
    • Ptolemy: Yes, the sun moves below the horizon.
    • Copernicus: No, the earth rotates, and the horizon occludes the sun.
  • Observation Incommensurability: Rival paradigms may be "seeing different things" when observing the same phenomenon.

Incommensurability of Observations

  • Example: Aristotle and Galileo looked at swinging stones.
    • Aristotle saw “constrained fall”.
    • Galileo saw a pendulum.
  • What we see depends on our paradigm.

Relativism

  • Relativism about truth: What is true is relative to ____
    • Your paradigm?
  • Kuhn: There is no “super-paradigm” that allows us to decide between rivals during a period of revolutionary science.
  • Incommensurability means we cannot easily compare rivals.
  • Does this mean there is no answer about which paradigm is better?
    • Not necessarily!

Relativism Discussion

  • Suppose Kuhn is right about incommensurability between rival paradigms, does this mean that there is no basis for choice?
  • Isn’t there a clear sense in which modern science is better than early science, even if the two are incommensurable?

Chapter 10

  • "I have argued so far only that paradigms are constitutive of science. Now I wish to display a sense in which they are constitutive of nature as well…"

The Duck-Rabbit Example

  • What were ducks in the scientist's world before the revolution are rabbits afterwards.

Religious Conversion

  • A scientist who embraces a new theory in physics, like the theory of relativity, doesn't just accept it because of evidence; they also adopt a new way of thinking about space, time, and gravity. This is a shift in fundamental beliefs, similar to a religious conversion.
  • Do we literally live in a different world after a religious conversion?
  • What does this analogy suggest about scientific revolutions?

Different Worlds?

  • Ch. 9: Our paradigm shapes how we view the world.
  • Ch. 10: Scientists with different paradigms inhabit different worlds.
  • Why is this so radical?
    • Denying a single reality implies denying a single perspective
  • Incommensurability makes comparison hard, but if scientific rivals are literally in different worlds, it becomes impossible.

Progress

  • Does science make progress?
    • Normal science makes clear, quantifiable progress.
    • Revolutions throws much of that progress away.
  • Is there progress through revolutions?
  • Later scientific theories are better than earlier ones for solving puzzles in the often quite different environments to which they are applied. That is not a relativist's position, and it displays the sense in which I am a convinced believer in scientific progress.

Final Thoughts

  • Myth: Kuhn showed that science is irrational—scientists are indoctrinated in a given paradigm, and there is no rational basis for adopting one paradigm over any other.
  • Normal science is essential for scientific progress and inevitably leads to crisis and eventually revolution.
  • Revolutions are not rule-governed, and incommensurability makes it hard to compare rival paradigms.
  • None of this means that objective progress is impossible, nor that science is irrational.

Summary

  • Revolutionary science occurs once we have rival paradigms.
  • Rival paradigms are incommensurable.
    • They disagree about the very things we use to evaluate hypotheses.
  • Ch. X: the proponents of competing paradigms practice their trades in different worlds.
  • Ultimately, one paradigm wins out by converting the non-believers.