La freccia e il cerchio
anno 7, numero 7, 2016
pp. 214-216

6.
Leonardo Merola
Considerations on the Physical world between illusions and clues

   Since ancient times scientists and philosophers have asked themselves: does an objective physical reality exist, the so-called “thing in itself” (onto- logical problem)? If the answer is yes, are we able to know it scientifically (epistemological problem)? Both the investigations interweave unavoidably because of the crucial role that the human being plays when he meets the alleged reality outside himself through his senses (or through his technolog- ical extensions such as sophisticated and complex devices and equipment) or when he formulates scientific theories and laws with his own thought and language, at the risk of making a mere consideration on himself that is a subjective representation of an unknowable world. We are thinking of Xe- nophanes of Colophon’ s opinion (VI century BCE) according to whom “if cattle and horses and lions had hands or could paint with their hands and create works such as men do, horses like horses and cattle like cattle also would depict the gods’ shapes and make their bodies of such a sort as the form they themselves have”. He had a drastic position, in contrast with re- ligion and superstition, but both positions coexist in the history of thought, superficially identified with materialism-idealism, and they have been fight- ing not only in words but sometimes they also represent the ideological basis for outright models of life and society.

The spider web of illusions…

   Let’s now go back to the fundamental question: is the physical world an “illusion” made up by our minds? Do we observe mere “shadows” like in the myth of Plato’s cave? And does the sensible experience tell us something “true” about reality? Are we perhaps deceived by the Cartesian “malignant genius” who arouses in us deceptive quite “credible” sensations? In physics, especially in the physics search for particles, we are always fighting against something similar: we observe facts and events, looking for interesting “signs” and we must manage to recognize and distinguish them from the “background”, that is from those facts or events presenting similar or alike properties to the ones we are looking for. In such cases there is no certainty, as, when asserting one thing or its opposite. At the most it is possible to state a certain level of probability. To give a real example: the search of new particles (i.e. in the high energy collisions protonroton at the Large Hadron Collider of the CERN) consists in identifying the particles produced by the decay of the new particle, paying attention that the observed particles do not come from other phenomena or known particles. In the case of the now famous discovery of the “Higgs boson”, announced at the CERN on the July , 2012 by both the international collaborations Atlas and Cms, we physicists assert that the observed events have a very low probability, one tenth of a millionth, of coming from background events and not from the Higgs particle. Unfortunately, if the devil decided to put his hoof in, it still could be possible! We are confident in the discovery only comparing experiments and with subsequent confirmation, until now never contradicted by facts.
   According to Goethe the most we can aim at is to investigate what is
accessible to our research, stopping respectfully before the inaccessible. On the contrary, according to Kant, something a priori is necessary i.e. the categories (among which for example the causal law) guiding sensations towards knowledge; hence comes the synthetic-a priori judgement, where the intervention of the human mind is indispensable. Thus we go back to Descartes’ philosophy according to which our mind is the protagonist of knowledge, because it is the only one able to go beyond the fragmentariness and lack of homogeneity of the sensitive material thanks to its innate ideas. For Mach, instead, (we are by then at the end of the nineteenth century) no reality exists beyond our sensations. The old contraposition between empiricism (Locke, Hume) and rationalism (Descartes) reveals two opposite ways of looking at the world or, rather, of looking at ourselves in the world. The excess of empiricism leads to scepticism and to solipsism («I am at the centre of every knowledge, there is nothing beyond myself») as after all in the ancient times Protagoras the sophist had asserted («man is the measure of everything») but the opposite risk is a metaphysic drift, as positivism with Comte properly maintained. The excess of such position leads to ascribing only a conventional aspect to scientific laws (Poincaré). Even Le Roy states: «The scientist creates the fact».
   “To describe how” (Kirchhoff and Mach’s position) or “to explain why” (position of the idealists Fichte, Schelling, Hegel) this is the question!
   In the first case we ask Science to search the relations and the recurring events among facts converting them into “factual” laws of nature; in the second case we would search the “causes” of phenomena and connect the events with necessary causal links. We may say that the concept of physical law and cause as the necessary link among natural phenomena were born with Leonardo da Vinci’s genius.
   Hume’s critique to the concept of causality is well known: there are no necessary causal relations, as it is only possible to state a non necessary relation of temporal sequence among the events. How far are we from Aristotle’s finalistic concept of Nature, from the concept of “form” as “cause” (in a theological sense) of the passage from the “matter” as a “power” to the form as an “act”!
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