Chapter VI of Kuhn, Structure of scientific revolutions (p. 53 - 56)
Kuhn-1962-structure-of-scientific-revolutions uses the paradigm shift from phlogiston to oxygen to illustrate why scientific-revolution cannot be understood as simple discrete events. Multiple scientists (Priestley and Lavoisier among others) contributed to “discovering oxygen,” but none can be said to have discovered it at a single moment. For Kuhn, discovery involves an extended process of conceptual assimilation.
This case also exemplifies the discontinuous (non-cumulative) nature of scientific-revolution. because there is an ontological, methodological, conceptual, and explanatory (what questions matter) discontinuity between the two paradigms. The two theories cannot be compared (incommensurability) and shows scientific-revolutions-as-changes-of-world-view.
Timeline of discovery of oxygen =
- Priestley pre-1775 = collected a gas released by heated red oxide of mercury (that we now know as oxygen) and defined it as nitrous oxide / “common air with less of its usual quantity of phlogiston”
- Lavoisier using Priestley’s experiments to build his idea called the gas as “air itself entire” = closer to modern oxygen but still incomplete concept
The problem that occurs is who first discovered oxygen, and when?
” ‘Oxygen was discovered,’ misleads by suggesting that discovering something is a single simple act assimilable to our usual (and also questionable) concept of seeing. That is why we so readily assume that discovering, like seeing or touching, should be unequivocally attributable to an individual and to a moment in time.” (Kuhn, p. 55)
If we require complete grasp of the oxygen paradigm to characterize the “discovery of oxygen” then nobody discovered oxygen until decades after it was already in use.
When we look back at past scientific revolutions from our current paradigm to define discoveries, we inevitable distort what actually happened. This is a consequence of incommensurability = the old and new paradigms are conceptually discontinuous, making it impossible to cleanly map concepts across the revolutionary divide.
Using the example of phlogiston vs. oxygen = when modern historians ask “who discovered oxygen?”, we are projecting our concept of oxygen backwards onto historical events. Because paradigms are discontinuous, discovery cannot be a single moment where someone “sees” oxygen for the first time. Instead, it is a collective effort, and only in retrospect do we identify a substance being discovered.
commitment to phlogiston paradigm
Scientists working with the phlogiston framework were unwilling to abandon it without compelling reason.
An anomaly within the phlogiston paradigm was that experimental evidence seemed to undermine phlogiston theory (weight gain when phlogiston was being lost seemed inconsistent). Rather than abandoning phlogiston, theorists at the time proposed that phlogiston has negative weight, an ad-hoc modification in an attempt to preserve the paradigm.
The phlogiston case exhibits typical symptoms of Kuhn-on-crisis-and-scientific-revolutions =
- multiple different versions of phlogiston theories emerged
- different phlogiston theories needed for different applications
- loss of consensus