In the case of Galileo’s experimental observations, the intervention of his mind manifested itself in extending the conclusion to the question: what angle corresponds to an infinitely smooth surface? And he gave the only possible answer: angle of zero degree, i.e., no inclination at all! From this he discovered one version of the first law of motion: on an infinitely smooth horizontal surface, an object moves for ever on its own. This is the real hypothesis! And one can argue that it started the entire field of physics. But, if we were to follow the observation-hypothesis-test triad, we would have to abandon the first law of motion, because every experiment performed in the laboratory disagrees with it: every object eventually comes to a stop on a horizontal surface. To move the object, a push or a pull is required, as Aristotle erroneously hypothesized in his book Physics.
The second law of motion could never have been discovered without the first law. If objects move on their own without the need for something to push them or pull them, why do they stop on a real surface? More generally, what causes a change in the state of motion of an object, which by the first law tends to move indefinitely on its own? Newton injected the answer from his mind by introducing the concept of force as that which changes the state of motion. But in order to make a precise statement, he had to introduce the concept of derivative as well, and write the second law of motion as a statement in calculus. The discovery of the second law required the invention of calculus!
The role of the human mind in the scientific process did not start with Galileo. The very notion of a geometric point is the injection of human thought in the conclusions drawn from countless experimental observations made on geometric figures by Egyptians, Babylonians, and early Greek mathematicians. A geometric point does not exist in nature just as an infinitely smooth surface does not exist. Yet, without the concept of a point that has no size, we would not have geometry, and without the concept of an infinitely smooth surface we would not have physics.
All human scientific knowledge has been acquired by the injection of the human mind in the observation-hypothesis-test triad. The triad alone does not create new knowledge.
If chemistry were to follow the popularly advertised scientific process, we would still be at the alchemy level! The notion of atoms, so crucial to the development of not just chemistry, but physics and the entire scientific enterprise, could never have been discovered by the triad. It was a human thought injected in the chemistry of early nineteenth century. This role of the human mind, which is neglected in the overly emphasized “hands-on” approach to the teaching of science to elementary school pupils, needs to be highlighted, if only to send the message that
to be a scientist, one not only has to be agile with one’s hands in doing experiments, but one also needs a capable mind.