This debate is particularly highlighted in the polemic which opposed at the beginning of the 18th century (from 1714 to 1716) Isaac Newton and Gottfried Wilhelm Leibniz in a famous epistolary exchange where Samuel Clarke made himself the lawyer of the English scholar. Centered on the status of space and time, the debate also includes personal innuendoes (quarrel over priority concerning the invention of integral calculus), epistemological backgrounds (realism of the physicist against idealism of the mathematician) and theological issues.
For Newton, space and time are (as the title of his fundamental work indicates: The Mathematical Principles of Natural Philosophy, 1687) part of the essential bases of all natural science. As coordinates for representing any phenomenon that occurs in nature, they indeed provide physics with the universal and objective framework it needs, the empty stage on which any story can be represented. This is why Newton calls them “absolute” (existing independently of the things that make up our world), perfectly homogeneous and neutral (indifferent to the things that can take place in them), and “infinite” (since everything begins and ends in them, while they themselves cannot, as a consequence, have any beginning or end or any limit whatsoever). They are somehow divine attributes or extensions of divine Mind as it conceives and contemplates its creation (“sensoria Dei” says Newton)… How space and time thus conceived differ from those we commonly experience, Newton calls them “true and mathematical” (symbol t of physical laws). The time of physics, for example, has always flowed uniformly, unrelated to anything external to it, and it would continue to flow even though there was no movement of any kind anywhere. It therefore differs from social time, which is regulated by natural movements that are always somewhat irregular and which are therefore necessarily measured approximately.
Leibniz, for his part, refuses to recognize in space and time the absolute and infinite characters which would make them divine attributes: they are creatures, properties of the created world, and, as such, they are partly linked to the set of created things and, of course, also limits. In a world that the Creator (to reflect his own perfection) intended to be as diverse, saturated, rich and harmonious as possible (“the best of all possible worlds”), space and time, far from existing by themselves are only a certain arrangement, or a certain general order between things. Both therefore do not exist in the manner of material things, nor are they their first conditions (as Newton wanted), but on the contrary they exist in the relations between these things, benefiting from a reality that is entirely derived from it. This explains the paradoxical reality that we have always recognized in time (mixture of being and non-being): it exists in fact as numbers exist (which come to number pre-existing things) or all mathematical idealities; it is (like space) a mental thing, a pure being of thought.
Emmanuel Kant combines in his own way the two opposite tendencies: to establish the realism of Newtonian science, he will dematerialize space and time. Indeed, questioning the conditions of possibility of our objective knowledge of nature, he seeks to account for the adequacy between the objects of the external world and the ideas that are formed in us. These ideas are constructed by the understanding on the basis of information provided by our senses. In other words, the experience we have of nature and the external world involves two operations: first, the reception in the sensibility of the raw data provided by the senses; second, the elaboration of these givens by the understanding which makes them objects of thought. But space and time are at the heart of the first of these operations… Everything we perceive is immediately located by us in space and time. Reception in the spatial form imprints on the sensible datum a mark of exteriority: the phenomena delivered to our sensibility are immediately identified as exterior to us and exterior to each other, which then makes it possible to give them a grandeur, a figure, and to establish relations between them… Reception in the temporal form, on the other hand, registers the phenomena according to the order in which they affect us. It marks those which are simultaneous, those which follow one another, and thereby it serves as the basis for any representation of movement or change…in us and outside of us. Time therefore belongs to our most intimate experience. It models, or rather it modulates, the intuition that our mind has of itself and of everything that happens to it. Constitutive of human sensibility, it is, according to Kant, the “form of the internal sense” by which we feel our own impressions, as space is the “form of the external sense” by which we feel the objects which come to be impressed in us. And since these two “forms of sensibility” are in us before any experience (since it is they which make it possible and found it), they are “a priori” (which does not necessarily mean innate) and “pure” in themselves of any empirical content (ready to receive and process any content)… Does this amount to making them anthropomorphic projections and all in all illusions? Certainly Kant denies them any reality in itself or absolute… and an extra-terrestrial or supra-human intelligence (which by definition would not be constrained like us by the conditions of sensibility) would free itself from time, for example, both in consciousness it would have of itself only in its knowledge of things. But for all that, space and time are not deprived of reality. On the contrary: they are indeed the condition of all our experiences and it is only in them that we can grasp any reality… and even our own reality as a sentient and thinking subject. Time (to stick with it) is therefore both in us and, consequently, in things as we experience and know them… In us? Out of us? It should rather be said that the alternative is loaded… insofar as the distinction of an outside and an inside only makes sense from the forms of space and time!
Henri Bergson built all his work on the distinction between “intimate duration” and a materialized and degraded time in things. But he too blurs the lines of an overly simplistic separation between inside and outside, mind and world. True time is that which wells up in the most intimate of our consciousness, in the disordered flood of impressions of all kinds, in the continual slippage of our interior states, in the gradual enrichment of our self. It is a simple duration, a pure and continuous duration, comparable to the flow of a fluid or the development of a melody. It is like a growth from within, the past continuing uninterruptedly into the present and this in turn spilling over into the future. It is the natural movement of consciousness, the impetus that gives it life. Pure duration is the form that the succession of our states of consciousness takes when our self allows itself to live, when it refrains from establishing a separation between the present state and the previous states. This duration is capricious, elastic, indivisible, irregular… Nothing to do with the domesticated time of social life that we measure with our watches. The latter is made artificially, tailor-made in a way, for the needs of practical life. In the common representation of time, we take advantage of the dual nature of movement (spatial and temporal) to reduce time to space and represent its flow with a line. Nothing could be easier then to divide this line as much as necessary to count units of time on it. But what is measured is always an interval delimited by fixed points (fictitious stops of time); the mobility of duration has evaporated, we are only dealing with space… This is why ordinary time (which is also that of Newton and of science, quantifiable and measurable) is in fact a distorted, standardized and normalized time, contaminated by space and practical concerns. Let us turn away from these attachments to restore consciousness to its freedom (which happens in dreaming or daydreaming), and we will find pure duration with its rhythm and its fantastic qualities: vital energy, pure, unpredictable, inventive, creative… Energy which wells up in the consciousness therefore, but just as well in the world provided that, beyond the particularization and the cadastralization imposed on it by our programs of action, we find its living totality. Because, freed from the filter of pragmatism, the world appears as an evolving and creative power, which unfolds continuously, in a tentacular way, which multiplies changes and initiatives of all kinds, which constantly invents new forms, unprecedented forms, as original, as unpredictable as are our own states of consciousness… The world, indeed, endures; it is duration…just like our consciousness. Against mechanistic and mathematical physics, it is the whole lesson of biology, which Bergson exposes in Creative Evolution of 1907.
(Includes texts from Wikipedia translated and adapted by Nicolae Sfetcu)