Read about the history of science and the expression ‘natural philosophy’ will soon appear. Participants in the Scientific Revolution called themselves natyral philosophers so, for example, the full title of Newton’s Principia was, in translation, The Mathematical Principles of Natural Philosophy). Natural philosophy is thus associated with the early modern break from Aristotle and the ancients with a new program based on observation and experiment. But, in a loose sense, natural philosophy was simply speculation about nature: the Greeks had certainly conceptualized and framed the way it was studied an interpreted, most notably through Aristotle’s four (be)causes that addressed questions of motion, change, and the essential nature of objects. Natural philosophy was originally placed under the general heading ‘philosophy’ and sat alongside metaphysics, logic, and moral philosophy before it was itself divided into the subjects botany, zoology, geology, and chemistry.
The Latin phrase philosophia naturalis was synonymous with physica in the curriculum of the medieval university, so those who studied the natural world were natural philosophers. Natural philosophy was therefore the particular way of explaining the world that was used by these scholastics. And here it was Aristotle’s natural philosophy that held sway from the 12th to the 17th centuries.
There were two aspects of Aristotelian science that are often ignored. First is the distinction between theoretical and practical knowledge, Aristotle’s episteme (theoretical knowledge or epistemology studied by free men of the city) and techne (how to make or do things: applied knowledge or technology which was often associated with manual labour). This was loosely equivalent in the later Latin to scientia and ars, sciences and the arts. This was the difference between explaining and manipulating nature. Part of Francis Bacon’s 17th century attack on Aristotleian scholasticism as being ‘more interested in verbal arguments than in changing nature for human benefit‘ was undermining this distinction – a distinction still continuing in the ideas of pure and aplied research. And, of course, (medieval) natural philosophy was closely aligned with theology in a way that science is not. Theology was an integral part of Newton’s world view.
It would seem that natural philosophy was not displaced but transformed during the Scientific Revolution. We emphasise the new scientific methodology that was adopted at this time but it was also a rise in the cultural status of mathematicians and practitioners of techne – those with the ability to affect change in the natural world through practical intervention – hence the mechanical philosophy that replaced Aristotelian organic metaphors. Aristotelians had been mistrustful of mathematicians because they were unclear how physical conclusions could be drawn from mathematical models.
The 19th century may be treated as the conclusion of natural philosophy, not just because this was when the word ‘scientist’ becomes accepted but because, from the 1840s on, science became a government-approved professionalized practice based in public research institutions, not just a diversion of the clergy and leasured gentlemen. The old medieval theology of natural philosophy also became unacceptable at this time as methodological naturalism became the norm in science: it was not acceptable for public scientists to publish supernatural explanations of the world. The merging of episteme with techne resulted in productive science that supported economic enterprise, improvements in scientific application indicating improvements in theories.
One interesting development of post-Baconian science is the ascendancy of practicality over theory, the assumption that techne demonstrated episteme or, expressed in modern terms, a more pragmatic or instrumental view of science … that theories are true because they work. There is the further point that though technology is clearly cumulative and progressive the explanations and theories that underpin it are not necessarily so. The prevailing view would hold that there can be no absolute distinction between observation and theory, that reasoning must have context.
Natural philosophy is generally associated with the Aristotelian ideal of science as a chain of logical deductions based on incontestable premises. We see a remnant of this in the now redundant hypothetico-deductive method thought to characterise good science. Though Aristotle’s method is now discredited it is clear that he was trying to express in logical form the perspective of inexorable determinacy of the world – which is an integral assumption of all science. The world has order – or logos as Aristotle would have said. Early scientists like Galileo and Robert Hooke described themselves as philosophers.