Modern Natural Science
The natural science founded by Galileo at the beginning of the seventeenth century and developed by Newton in the second half of the same century did not radically differ from the classical paradigm.
A decisive difference, however, consisted in the methodological decision to give up the frustrating illusion to grasp the essence of the “natural substances” (i.e. of the material bodies) by “speculation” (i.e. by an intellectual intuition), and restrict our attention to a few selected accidents (i.e. to certain mathematizable properties of the physical bodies). Instead of the speculative intellectual intuition, a new method of inquiry was invented (the experimental method), consisting in formulating a hypothesis regarding the phenomenon under consideration, and testing by an appropriate artificial experiment the consequences of the said hypothesis. This new way of making natural philosophy (as it continued to be called) remained realist in both the classical senses: (i) because the object of investigation was considered to be a reality independent of the human investigation (the new science was concerned with “real accidents” to use the literal phrase of Galileo), and (ii) because this investigation was considered to attain a true knowledge of the said delimited domain of reality. Therefore, truth still was the fundamental characteristic attributed to this new form of knowledge.[10]It is worth noting that working scientists, such as Galileo and Newton, were not affected by that strange “dualistic” presupposition according to which what we know are our ideas and not reality, and this has remained a constant attitude of scientists until the end of the nineteenth century. In particular, this realist consideration of natural science rapidly produced in Western culture the conviction not only that it was a genuine form of knowledge, but even the paradigm of knowledge as such (as is explicitly stated in Kant's Preface to the second edition of the Critique of Pure Reason).
In the nineteenth century, positivism claimed that science was actually the only genuine form of knowledge, having overcome the illusionary pretentions of theological and metaphysical approaches to reality. Positivism, however, was affected by an inadequate appreciation of the role of reason in the construction of science. Galileo, who had so strongly underscored the role of concrete observations, measurements and experimental testing of hypotheses, had fully understood the indispensable role of reason that must even be ready to “do violence to sense” in order to uncover the real nature of phenomena by advancing a hypothesis that can finally be experimentally confirmed. Or, to give another example, when he formulated the principle of inertia, for which no empirical evidence exists, but must be admitted only through cogent reasoning. Positivism, on the contrary, was prisoner of a radical empiricism, reducing science to a diligent record of uninterpreted data that allegedly express sense perceptions (the only bearer of knowledge). Theoretical constructions were downplayed to useful tools for organizing perceptions for practical purposes, but without cognitive purport. This is notoriously the position of Ernst Mach in which we can see a clear forerunner of scientific anti-realism.3