Natural philosophy

Natural philosophy or the philosophy of nature, known in Latin as philosophia naturalis, is a term applied to the objective study of nature and the physical universe before the development of modern science. It is considered the precursor of what is now called natural science, especially physics.

Forms of science historically developed out of philosophy or more specifically natural philosophy. At older universities, long-established Chairs of Natural Philosophy are nowadays occupied mainly by professors of physics. Our notions of science and scientists date only to the 19th century. Before then, the word "science" simply meant knowledge and the label of scientist did not exist. Issac Newton's 1687 scientific treatise is known as The Mathematical Principles of Natural Philosophy.

Origin of the term
Natural philosophy was the term whose usage preceded our current term science in the sense that prior to the replacement of the term natural philosophy with the term science, the term science was used exclusively (and comparatively rarely) as a synonym for knowledge or study and when the subject of that knowledge or study was 'the workings of nature', then the term natural philosophy would be used. Natural philosophy became science (scientia in Latin, which means "knowledge") when inductive methods of knowledge acquisition, known as the scientific method became emphasized over pure deduction.

Figures in natural philosophy
While proposals for a much more 'inquisitive' and practical approach to the study of nature originated with Francis Bacon, Robert Boyle wrote what is considered to be a seminal work on the distinction between nature and metaphysics called A Free Enquiry into the Vulgarly Received Notion of Nature. This book, written in 1686, marked the point where the scene was set for natural philosophy to turn into science. It represented a radical departure from the scholasticism of the Middle Ages, and while features of natural philosophy retained some of the trappings of the elitism associated with its precursor, natural philosophy was arguably empirical while previous attempts to describe nature were not. An important distinguishing characteristic of science and natural philosophy is the fact that natural philosophers generally did not feel compelled to test their ideas in a practical way. Instead, they observed phenomena and came up with 'philosophical' conclusions.

Boyle, while he is the first to fully embrace such an approach in both his experimental endeavours and his writings, shares with Bacon (and Galileo who was the inspiration in these matters for both Bacon and Boyle) a conviction that practical experimental observation was the key to a more satisfactory understanding of nature than would have otherwise been sought through either exclusive reference to received authority or a purely speculative approach.

Although Galileo's 'natural philosophy' is hardly distinguishable from science in many ways, the connection between his experiments and his writings about them is characteristically philosophical, rather than being cluttered with the results of meticulously recorded observational detail of practical scientific research, in the way that Boyle subsequently advocated.

Even though Boyle described what he practiced as 'natural philosophy', the very innovations that Boyle introduced can be seen as a basis for delineating a transition from proto-science to science. Among these innovations are an insistence upon the publication of detailed experimental results, including the results of unsuccessful experiments; and also a requirement for the replication of experiments as a means of validating observational claims.

Thus Boyle's application of the term 'natural philosophy' to his own work may be regarded an anachronistic conflation with earlier proto-science, since the distinction between the terms 'natural philosophy' and 'science' only arose after Boyle's passing.

Boyle would therefore describe his work as 'natural philosophy', whereas we would describe it as 'science'; and yet Boyle's use was correct for his own time. Nonetheless, he is in many ways the architect of the modern distinction between the two terms.

The ancient emphasis on deduction has its representative in Aristotle's Organum, and the new emphasis on induction and research has its representative in Francis Bacon's treatise Novum Organum.

Descartes formulation
In René Descartes' metaphysical system of dualism, there are two kinds of substance: matter and mind. According to this system, everything which is "matter" is deterministic and natural -- and so belongs to natural philosophy -- and everything which is "mind" is volitional and non-natural, and falls outside the domain of philosophy of nature.