Steven Johnson utilities 3 different models in the history of science to explore and explain changes within the history of science.
One of these models, the progressive (Great Man) history, carries its historical change by the accomplishments and discoveries by people of grandeur. In general history we explore history this way to understand varying personal perspectives of history. Like for example, Edison created machines that contributed to the creation of electrical professions.
Another model, the paradigm shift (or otherwise known as Kuhn’s perspective of history), is determined by the Development-by-accumulation model. From the text “as a series of indisputable facts unearthed one after another, each breakthrough another step to a definitive truth.” best explains this model, and when used in a “for instance”, it would look like this. The truth some scientists seek is where we come from, and with learning about our biology, our psychology, and our overall atomic make up, we are closer to understanding how we got here.
Finally the last model has to do with the ecosystem theory. Now today we are well aware that ecosystems exist and that they are very important to understanding a species. a great example of this is that Paleontologists work with biologists and geologists to better understand the land and climate in which dinosaurs lived. But back in Priestley’s day, it wouldn’t be another hundred years or so when humankind would be making connections between an animals ecosystem and their biology. So the ecosystem theory in early practice would be simply observations of how animals interacted with the world.
Johnson describes one of the methods Priestly used to discover Oxygen, was that Priestly conducted an experiment with plants that he originally had done as a child with animals. This in relation to the historical models discussed earlier could be a form of paradigm shift. From knowing about his past experience he can conduct a similar experience with plants. The idea in question was that would a plant become feeble or die when deprived of the air in an enclosed space. Priestley tested this by burning the air inside a contained container and then waited for the plant to die. But after a while the plant still remained alive and to see if there was any more air in the jar to burn, the match/candle equivalent burned as if there was air in the jar before, like how today we know trees take in carbon dioxide and release oxygen, and we or other organisms burn up oxygen to function. After testing and retesting the experiment, this led Priestly to believe that plants give off their own air. This idea eventually lead him to the discovery of oxygen.