3.3.2 Big Shifts in Scientific Thinking Notes

Scientific Paradigm Shifts Have Redefined How We Understand the World

1. Sometimes science goes through revolutions that replace entire frameworks of understanding.
2. Philosopher Thomas Kuhn called these moments paradigm shifts.
3. They aren't small updates but wholesale changes in the assumptions that guide science.
4. This directly challenges the idea that science provides steady, linear progress toward truth, suggesting instead that knowledge can flip dramatically, forcing us to rethink what counts as reliable evidence, what certainty means, and what “progress” really looks like.

What Are Paradigm Shifts?

1. Paradigm shifts happen when the assumptions of a field no longer explain the evidence.
2. Scientists work within a framework: what questions are worth asking, what counts as good methods, and what theories are “normal.”
3. Over time, anomalies build up and eventually, a new framework emerges that explains the anomalies better.
4. The old paradigm collapses, and a new one takes its place.

Paradigm Shifts Show How "Fragile" Science Is

1. The heliocentric model was one of the most dramatic shifts in scientific thinking.
2. For centuries, people assumed the Earth sat at the center of the universe, a view that lined up neatly with religious teachings about humanity’s special place.
3. Copernicus challenged that view, and Galileo’s telescopic observations along with Kepler’s laws of planetary motion eventually provided strong evidence that the Sun, not Earth, was central.
4. The Church resisted fiercely not because the evidence was weak but because accepting it meant giving up cultural authority.
5. This is a reminder that in science, evidence alone doesn’t always decide what counts as knowledge, because social power matters too.

Example

• The same dynamic appeared in medicine with the germ theory of disease.
• For centuries, doctors explained illness through miasma (bad air”) or humoral imbalance.
• Pasteur and Koch, using microscopes, showed microorganisms were the real cause. This revolutionized medicine with hygiene, vaccines, and antibiotics.
• Yet many physicians resisted, since accepting germs meant admitting their training and traditions were wrong.