Case Study 2: Plate Tectonics — The Paradigm Shift That Didn't Require Funerals
The acceptance of plate tectonics in the late 1960s is one of the most dramatic paradigm shifts in the history of science — and one that challenges Planck's principle directly.
The Shift
Between approximately 1965 and 1968, the earth sciences underwent a revolution. Continental drift — dismissed for 50 years — was accepted as plate tectonics in roughly 3-5 years. The same generation of geophysicists that had rejected the idea largely accepted it.
Why It Was Fast
The plate tectonics shift bypassed Planck's principle through circumvention: the discovery of seafloor spreading and magnetic anomalies provided an entirely new line of evidence that made the "no mechanism" objection obsolete. The defenders didn't need to be persuaded that Wegener's original evidence was stronger than they thought. They needed to accept that a new mechanism (mantle convection driving plate motion) existed — and the evidence for the mechanism was independent, convergent, and overwhelming.
The Six-Variable Analysis
| Variable | Assessment |
|---|---|
| Evidence clarity | Very high — magnetic stripes visible in data |
| Switching cost | Moderate — geologists retrained but basic skills transferred |
| Defender power | Moderate — no commercial interest in fixed continents |
| External evidence | Multiple independent lines (paleomagnetism, seismology, ocean floor) |
| Correction mode | Pure circumvention — new mechanism rendered old objection obsolete |
| Crisis | None — but evidence was so overwhelming it didn't need a crisis |
The Kuhnian Anomaly
Interestingly, the plate tectonics shift is one of the cases that least fits Kuhn's model. Kuhn emphasized crisis as a precursor to paradigm shift. But plate tectonics didn't require a crisis — the fixed-continent paradigm wasn't failing in any dramatic way. The new evidence was simply so compelling that the old paradigm was abandoned even without an anomaly crisis.
This suggests that Kuhn's model (and Planck's principle) may overstate the role of crisis and generational replacement. When circumventing evidence is strong enough, correction can occur rapidly and without crisis — even within the same generation of practitioners.
Discussion Questions
- If circumventing evidence can produce paradigm shifts within a single generation, why is this not the norm? What conditions must be present for circumvention to work?
- The plate tectonics shift took 3-5 years. The ozone correction took ~2 years. What structural features determine whether fast correction takes years or months?
- Apply the plate tectonics model to a current stalled correction: what circumventing evidence would be needed?
References
- Oreskes, N. (1999). The Rejection of Continental Drift. Oxford University Press. (Tier 1)
- Research on the timing and dynamics of the plate tectonics revolution has been conducted by multiple historians of science. (Tier 2)