Paradigm Shifts or Paradigm Evolution?

The leading historiographical narrative of science history today is Thomas Kuhn's concept of paradigm shifts, where consecutive scientific revolutions replace the previous paradigm following the establishment of the 'first universally acquired paradigm.' However, it might be more accurate to view these successive paradigms as evolving theories rather than isolated phenomena displacing each other entirely.

Considering scientific theories as evolving offers many useful implications, but first, we need to understand the structure Kuhn attributes to scientific revolutions. It is noteworthy that when we hear 'Scientific Revolution,' we usually think specifically about the period between the 16th and early 18th centuries. However, this period was labeled as such only in the 20th century. Kuhn disagrees with the implication that revolutions stopped after this time.

The anatomy of a scientific revolution begins before establishing the 'first universally accepted paradigm,' or normalcy—valid knowledge at a particular time. Initially, various schools of thought attempt explanations until one becomes dominant through rigorous debate. Inevitably, anomalies emerge, challenging the paradigm. For example, spontaneous generation, originating from Aristotle, faced critical anomalies eventually leading Francesco Redi to replace it in the 17th century.

Kuhn's illustration from optics further demonstrates this process. Newton's corpuscular theory, detailed in "Opticks" (1704), initially explained reflection and refraction, viewing light as particles. Fresnel and Young subsequently replaced this theory, demonstrating light as transverse waves. However, an evolutionary narrative better captures the later emergence of wave-particle duality proposed by James Clerk Maxwell in the 20th century, integrating elements from both previous paradigms.

Kuhn's approach also highlights diminishing significance of key figures across paradigms. Newton's contributions remain influential in various scientific fields but not in optics to the same degree. Kuhn notably cites multiple claimants (Scheele, Priestley, Lavoisier) for the discovery of oxygen, reinforcing the idea that scientific advancement moves beyond single discoverers.

The deliberate example of spontaneous generation highlights another significant evolutionary perspective. Although the focus during the Scientific Revolution was primarily astronomy, mathematics, and physics, paradigm shifts occurred across all natural sciences. Aristotle's geocentric model became dominant but struggled with anomalies such as Mercury's retrograde motion. Ptolemy later refined this model with epicycles and deferents, attempting to reconcile these anomalies.

Copernicus retained many Ptolemaic elements in his heliocentric model, including uniform circular motion and crystalline spheres. Tycho Brahe's observations improved planetary positioning accuracy and further adjusted the model, placing the planets orbiting the sun but keeping Earth central. Galileo Galilei then emphasized empirical evidence, influenced by Martin Luther's notion of plainly explaining complex truths. Galileo's trials and advocacy for inductive reasoning significantly influenced scientific discourse, contributing to the establishment of the Royal Society. Francis Bacon and Robert Boyle advanced empirical approaches further, laying the foundations for today's scientific method, which itself evolved through thinkers like Henri Poincaré and Karl Popper.

Using evolutionary biology as an analogy, scientific fields evolve and diversify into entirely new disciplines (akin to speciation). Kuhn's idea of revolutionary displacement is problematic, as each new paradigm builds upon previous knowledge rather than completely replacing it. Historical examples clearly demonstrate that while some aspects are replaced, others persist and evolve. E.H. Carr supports this non-circular evolution, arguing that progress emerges through interaction and reciprocal development rather than simple cyclical displacement.

Accepting an evolutionary historiography rather than a revolutionary one allows greater appreciation for interdisciplinary convergence, emergence of new scientific fields, and a reduced reliance on individual scientific heroes. Kuhn himself acknowledges that competing pre-paradigmatic schools of thought are continually engaging and influencing each other, further underscoring evolution rather than isolated revolutionary cycles. Viewing scientific progress as evolutionary aligns with Kuhn's own arguments and provides a richer, more nuanced understanding of scientific history.