ARCHITECTURAL RATIONALISM. -
Ever since the times of ancient classicism, first in Greece and then in Rome, certain "laws" or "rules" were established to which the forms and proportions of architectural members must conform. These "rules" and "laws" were codified several times over the course of the centuries (v. ARCHITECTURAL ORDERS).
They have their foundation in the very principle of the evolutionism of those forms and proportions, according to which the column would derive, for example, from the trunk of a tree, and the facade of the Parthenon, in its fundamental scheme, would take up the theme of the facade of the hut. Moreover, at times those same evolutionist theories were rendered even more complex by a certain anthropomorphism, according to which, in the view of some, the ancient Greeks would have drawn inspiration for the definition of their architectural "laws" from the perfect harmony of the human limbs.
As is easy to deduce, implicit in such theories is the concept of the initial "functionality" or "rationality" or, better still, reasonableness of the various elements and the various architectural members. From this there also derives the necessity of admitting the possible atrophy and therefore the transience — determined by disuse — of those elements and those members now destined for a merely decorative function. By logical steps one can therefore understand how, toward the end of the seventeenth century and over the course of the eighteenth, with the spread of the mentality that generated Enlightenment rationalism, and through the natural satiation of Baroque and Rococo taste, there came into favor architectural theories, already previously adumbrated as well (for example, by Gallaccini), which postulated for architecture the application of the same laws defined by Galileo in the fields of mechanics. The teachings of Carlo Lodoli and subsequently of Algarotti, Temanza, Memmo, Milizia and Pini — to cite only a few names among those of the Italian architectural theorists of the eighteenth century — then insisted that the use of every architecture be clear, even in its exterior aspect, and that every architectural element employed in that architecture have its own precise function. Every architectural form was thus to arise from a precise constructive reason, and every material was to be used according to its own characteristics and possibilities of employment. Such theories, which had the widest diffusion in the second half of the eighteenth century, at the time when Rococo taste was exhausting itself, laid the premises — precisely theoretical — for an architecture that in fact was not to be born then. Indeed, at that time, the demand for simpler and more straightforward architectural forms was answered, on the part of the practitioners of courtly architectural art, with the use of the forms that had been proper to ancient architecture, at that time investigated by archaeologists with new precision and scientific method (v. NEOCLASSICISM).
Yet if this happened in the fields of courtly architecture, where the Neoclassical forms were soon succeeded by the purist, and then the Romantic, and then again those of the eclecticism proper to the second half of the nineteenth century, in the realization of the first industrial buildings — that is, destined to house machines and created for the needs of machines — there came almost inadvertently to be applied, albeit without any stylistic requirement, that is, without any aspiration to beauty, precisely those principles that the theorists of architectural rationalism had by then long since enunciated.
One can therefore distinguish throughout the course of the nineteenth century a twofold architectural current. One, the courtly one, of ceremonial buildings, in which the forms of the ancient styles and orders are taken up with various temperings and varieties (it is essentially the work of those nineteenth-century architects who were above all professors of architectural drawing); the other is industrial architecture, the architecture of factories, the one determined, in its forms and in the very character of its structures, exclusively by the necessities of their use and by the needs of machines; that is, the architecture of engineers. In any case it was at the beginning of our century that this functional or rational architecture, in which, that is — perhaps it is worth repeating — the various parts and elements are determined, even in their appearance and in the choice of materials, by the requirements of their function and reason, assumed dignity and came to be widely understood as a new plastic-constructive style.
Such a style, while it intends to respond to the demands of functionalism and architectural rationalism, tends essentially toward "spatial creation." That is, toward the definition and harmonization of that modern architectural space which, though it cannot be determined by precise laws and rules, pursues plastic rhythms of high expressiveness and clarity, in which the demands of technique and the free flight of fantasy, finding a perfect accord, originate the artistic fact, that is, become art.