Giovanni Battista (Giambattista) Vico or Vigo (23 June 1668 – 23 January 1744) was an Italian political philosopher, rhetorician, historian, and jurist. A critic of modern rationalism and apologist of classical antiquity, Vico's magnum opus is Principi di Scienza Nuova d'intorno alla Comune Natura delle Nazioni, often published in English as New Science, which may be literally translated as "Principles / Origins of New / Renewed Science About / Surrounding the Common Nature of Nations". The work is explicitly presented as a "science of reasoning" (Scienza di ragionare), and includes a dialectic between axioms (authoritative maxims) and "reasonings" (ragionamenti) linking and clarifying the axioms. Vico is often claimed to have inaugurated modern philosophy of history, although the term is not found in his text (Vico speaks of a "history of philosophy narrated philosophically"). He is otherwise well known for noting that verum esse ipsum factum ("true itself is fact" or "the true itself is made"), a proposition that has been read as an early instance of constructivist epistemology. While Vico was not, strictly speaking, a historicist, interest in him has often been driven by historicists (such as Isaiah Berlin and Hayden White).

Born to a bookseller and the daughter of a carriage maker in Naples, Italy, Vico attended a series of grammar schools, but ill health and dissatisfaction with Jesuit scholasticism led to home schooling.

After a bout of typhus in 1686, Vico accepted a tutoring position in Vatolla (a Frazione of the comune of Perdifumo), south of Salerno, that would last for nine years. In 1699, he married a childhood friend, Teresa Destito, and took a chair in rhetoric at the University of Naples. Throughout his career, Vico would aspire to, but never attain, the more respectable chair of jurisprudence. In 1734, however, he was appointed royal historiographer by Charles III, king of Naples, and was afforded a salary far surpassing that of his professorship. Vico retained the chair of rhetoric until ill health forced him to retire in 1741.

Vico is best known for his verum factum principle, first formulated in 1710 as part of his De Italorum Sapientia. The principle states that truth is verified through creation or invention and not, as per Descartes, through observation: “The criterion and rule of the true is to have made it. Accordingly, our clear and distinct idea of the mind cannot be a criterion of the mind itself, still less of other truths. For while the mind perceives itself, it does not make itself.” This criterion for truth would later shape the history of civilization in Vico’s opus, the Scienza Nuova (The New Science, 1725), because he would argue that civil life – like mathematics – is wholly constructed.

Relying on a complex etymology, Vico argues in the Scienza Nuova that civilization develops in a recurring cycle (ricorso) of three ages: the divine, the heroic, and the human. Each age exhibits distinct political and social features and can be characterized by master tropes or figures of language. The giganti of the divine age rely on metaphor to compare, and thus comprehend, human and natural phenomena. In the heroic age, metonymy and synecdoche support the development of feudal or monarchic institutions embodied by idealized figures. The final age is characterized by popular democracy and reflection via irony; in this epoch, the rise of rationality leads to barbarie della reflessione or barbarism of reflection, and civilization descends once more into the poetic era. Taken together, the recurring cycle of three ages – common to every nation – constitutes for Vico a storia ideale eterna or ideal eternal history.

Vico’s major work was poorly received during his own life but has since inspired a cadre of famous thinkers and artists, including Karl Marx. Later his work was received more favourably as in the case of Lord Monboddo to whom he was compared in a modern treatise.

Vico's version of rhetoric is often seen as the result of both his humanist and pedagogic concerns. In De Nostri Temporis Studiorum Ratione ("On the Order of the Scholarly Disciplines of Our Times"), presented at the commencement ceremonies of 1708, Vico argued that whoever “intends a career in public life, whether in the courts, the senate, or the pulpit” should be taught to “master the art of topics and defend both sides of a controversy, be it on nature, man, or politics, in a freer and brighter style of expression, so he can learn to draw on those arguments which are most probable and have the greatest degree of verisimilitude” (however, in his "Scienza Nuova", Vico denounces as "false eloquence" one defending both sides in controversies). As Royal Professor of Latin Eloquence, it was Vico’s task to prepare students for higher studies in law and jurisprudence. His lessons thus dealt with the formal aspects of the rhetorical canon, including arrangement and delivery. Yet as the above oration also makes clear, Vico chose to emphasize the Aristotelian connection of rhetoric with dialectic or logic, thereby reconnecting rhetoric to ends (or topics) as their center. Vico's objection to modern rhetoric is that it cuts itself off from common sense (sensus communis), as the sense common to all men. In his lectures and throughout the body of his work, Vico's rhetoric begins from a central argument or "middle term" (medius terminus) which it then sets out of clarify by following the order of things as they arise in our experience. Probability and circumstance retain their proportionate importance, and discovery – reliant upon topics or loci – supersedes axioms derived through reflective abstraction. In the tradition of classical Roman rhetoric, Vico sets out to educate the orator as the deliverer of the "oratio", a speech having "ratio" or reason / order at its heart. What is essential to the oratory art (as the Greek rhetorike) is the orderly link between common sense and an end commensurate to it — an end that is not imposed upon the imagination from above (in the manner of the moderns and a certain dogmatic form of Christianity), but that is drawn out of common sense itself. In the tradition of Socrates and Cicero, Vico's real orator or rhetorician will serve as midwife in the birth of "the true" (as a form or idea) out of "the certain" (as the confusion or ignorance of the student's particularized mind).

Vico's rediscovery of "the most ancient wisdom" of the senses (a wisdom that is "human foolishness" or humana stultitia), his emphasis on the importance of civic life, and his professional obligations remind us of the humanist tradition. He would call for a maieutic or jurisprudential oratory art against the grain of the modern privileging of a dogmatic form of reason in what he called the “geometrical method” of Descartes and the Port - Royal logicians.

As he relates in his autobiography, Vico returned to Naples from Vatolla to find “the physics of Descartes at the height of its renown among the established men of letters.” Developments in both metaphysics and the natural sciences abounded as the result of Cartesianism. Widely disseminated by the Port Royal Logic of Antoine Arnauld and Pierre Nicole, Descartes’ method was rooted in verification: the only path to truth, and thus knowledge, was through axioms derived from observation. Descartes’ insistence that the “sure and indubitable” (or, "clear and distinct") should form the basis of reasoning had an obvious impact on the prevailing views of logic and discourse. Studies in rhetoric – indeed all studies concerned with civic discourse and the realm of probable truths – met with increasing disdain.

Vico’s humanism and professional concerns prompted an obvious response that he would develop throughout the course of his writings: the realms of verifiable truth and human concern share only a slight overlap, yet reasoning is required in equal measure in both spheres. One of the clearest and earliest forms of this argument is available in the De Italorum Sapientia, where Vico argues that “to introduce geometrical method into practical life is ‘like trying to go mad with the rules of reason,’ attempting to proceed by a straight line among the tortuosities of life, as though human affairs were not ruled by capriciousness, temerity, opportunity, and chance. Similarly, to arrange a political speech according to the precepts of geometrical method is equivalent to stripping it of any acute remarks and to uttering nothing but pedestrian lines of argument.” Vico’s position here and in later works is not that the Cartesian method is irrelevant, but that its application cannot be extended to the civic sphere. Instead of confining reason to a string of verifiable axioms, Vico suggests (along with the ancients) that appeals to phronêsis or practical wisdom must also be made, as do appeals to the various components of persuasion that comprise rhetoric. Vico would reproduce this argument consistently throughout his works, and would use it as a central tenet of the Scienza Nuova.

In 1720, Vico began work on the Scienza Nuova – his self - proclaimed masterpiece – as part of a treatise on Universal rights. Although a full volume was originally to be sponsored by Cardinal Corsini (the future Pope Clement XII), Vico was forced to finance the publication himself after the Cardinal pleaded financial difficulty and withdrew his patronage. The first edition of the New Science (Scienza Nuova, rather than Nuova Scienza, for which Galileo had been known) appeared in 1725, and a second, reworked version was published in 1730; neither was well received during Vico’s lifetime.

Vico’s humanism (his returning to a pre-modern form of reasoning), his interest in classical rhetoric and philology, and his response to Descartes contribute to the philosophical foundations for the second Scienza Nuova. Through an elaborate Latin etymology, Vico establishes not only the distinguishing features of first humans, but also how early civilization developed out of a sensus communis or common (not collective) sense. Beginning with the first form of authority intuited by the giganti or early humans and transposed in their first "mute" or "sign" language, Vico concludes that “first, or vulgar, wisdom was poetic in nature.” This observation is not an aesthetic one, but rather points to the capacity inherent in all men to imagine meaning via comparison and to reach a communal "conscience" or "prejudice" about their surroundings. The metaphors that define the poetic age gradually yield to the first civic discourse, finally leading to a time characterized by "full - fledged reason" (ragione tutta spiegata), in which reason and right are exposed to the point that they vanish into their own superficial appearance. At this point, speech returns to its primitive condition, and with it men. Hence the "recurring" (ricorso) of life to "barbarism" (barbarie). It is by way of warning his age and those stemming from it of the danger of seeking truth in clear and distinct ideas blinding us to the real depths of life, that Vico calls our attention back to a classical art of moderating the course of human things, lest the liberty enjoyed in the "Republic" be supplanted by the anarchic tyranny of the senses. Crucial to Vico's work remains a subtle criticism of all attempts to impose universality upon particularity, as if ex nihilo. Instead, Vico attempts to always let "the true" emerge out of "the certain" through innumerable stories and anecdotes drawn mostly from the history of Greece and Rome and from the Bible. Here, reason does not attempt to overcome the poetic dimension of life and speech, but to moderate its impulses so as to safeguard civil life.

While the transfer from divine to heroic to human ages is, for Vico, marked by shifts in the tropological nature of language, the inventional aspect of the poetic principle remains constant. When referring to “poets”, Vico intends to evoke the original Greek sense of “creators”. In the Scienza Nuova, then, the verum factum principle first put forth in De Italorum Sapientia remains central. As such, the notion of topics as the loci or places of invention (put forth by Aristotle and developed throughout classical rhetoric) serves as the foundation for "the true", and thus, as the underlying principle of sensus communis and civic discourse. The development of laws that shape the social and political character of each age is informed as much by master tropes as by those topics deemed acceptable in each era. Thus, for the rudimentary civilization of the divine age, sensory topics are employed to develop laws applicable on an individual basis. These laws expand as metonymy and synecdoche enable notions of sovereign rule in the heroic age; accordingly, acceptable topics expand to include notions of class and division. In the final, human age, the reflection that enables popular democracy requires appeals to any and all topics to achieve a common, rational law that is universally applicable. The development of civilization in Vico’s storia ideale eterna, then, is rooted in the first canon of rhetoric, as invention via loci shapes both the creation of and discourse about civil life.

Isaiah Berlin has devoted attention to Vico as a critic of the Enlightenment and a significant humanist and culture theorist.