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No. 11, May 1998
Girolamo Cardano: historia, or the knowledge of the particular


No. 13 - Dec 2000 (PDF)

No. 12 - Sep 1999

No. 11 - May 1998

No. 10 - Jun 1997

Michelangelo Ferraro on Nancy G. Siraisi, The Clock and the Mirror. Girolamo Cardano and Renaissance Medicine, Princeton University Press, 1997.

In the hierarchy of values inherent in Aristotelian and Scholastic knowledge, the vast universe of natural things, the singulares rerum species, cannot be the object of true Scientia. The infinity of specific determinations, far from being as immediately intelligible as universals, is to be understood through the "mean channel" of empirical experience.

The long chain of the "contingent" stretches from the huge variety of forms in minerals and plants, to the complexity of animal bodies, and the impalpable qualities of souls. This vast world of -res- is tamed with difficulty by a long list of arts, of patient and perceptive disciplines, accustomed to the changeable follies of the individual. These arts, historia naturalis, astrology, alchemy, medicine, politics, historia gestarum etc., are all humble "mechanical" handmaids of theology and metaphysics.

From the time of Hippocrates, the theoretical and physiological aspects of medicine were based on the so-called theory of humours, corresponding in the body to the elements of Aristotle, themselves not exactly empirical. In practice, however, medicine maintained an interest in the individual, which was reflected in the manuscript volumes of clinical cases and therapeutic solutions. These volumes are a constant in the entire history of western medicine, often as silent witnesses. As is well-known, it will fall to the early modern age to give back a higher cultural dignity to the arts, and its infinite objects. In this period, collectors of particular events, of phenomena, and of natural objects, will all argue for the epistemological validity and practical utility of probable knowledge, abandoning the obsession with certainty.

The Renaissance therefore emerges as the period when, at various levels, there is a revaluation of natural objects and the disciplines that deal with them. Consequently the epistemological attitude necessary for this kind of knowledge, the fruit not so much of deductions as of comparing things, making analogies, and accumulating data, is also revalued. The term "experience" pervades Renaissance culture in all its various meanings, but primarily as empirical experience, or knowledge understood as the fruit of the sensory observation of things, qualities and events. The revaluation of this kind of knowledge brings with it the growth and the revaluation of the literary genre that expresses it, i.e. the historia, or repertory of the observation of objects and of specific events.

The "Shapin thesis" attributed the origin of the epistemology of experience on which the "experimental" sciences are founded mainly to Bacon, and the work of the Royal Society in the seventeenth century. Recent studies (Eamon 1996, Findlen 1994, and others), have on the other hand emphasized the need to backdate the origin of this methodological direction by a century or two, at least as far back as the astronomers, engineers, encyclopedists, collectors, philologians, esoterics, and doctors of Renaissance Europe.

One of the protagonists of this "resurgence of historia" and its method is undoubtedly the Milanese Girolamo Cardano, the subject of Nancy G. Siraisi's readable and unfussy recent book. She concentrates on Cardano's medical writings, where continuous references to works of an encyclopedic, astrological, and autobiographical character are not lacking. His mathematical writings, though, are not often mentioned.

In the first part of the book Siraisi defines what we may call the sociological scope of Cardano's varied output. She notices that between 1540 and 1560 Cardano published in northern Europe his astrological and encyclopedic works as well as those of moral philosophy, which together made him well known throughout Europe. But his medical writings were published in Italy, and they were dedicated to people who were influential in Italian cultural and political circles. Siraisi points out that, although Cardano's most innovatory ideas were produced outside the Schools (as was the case with many original works of the early sixteenth century), Cardano himself always aspired to become a part of the cultural aristocracy of university lecturers and doctors in the Colleges. Yet although his medical treatises remain by and large in the tradition of Hippocrates and Galen, Cardano's relationship with the cultural institutions of his time was not an easy one; it is enough to recall his short and troubled university career between Pavia and Bologna.

His many enemies in academic circles are often accounted for by his aggressive character, but we should remember that Cardano was one of a number of Renaissance magicians, like Cornelius Agrippa, Della Porta, and Fludd, etc., who moved precariously close to heresy, compared to the official culture of the universities. Our interest in Cardano lies in the emblematic character of his cultural outlook, which Siraisi brings out. In his De subtilitate of 1550, Cardano clarifies his cosmology and the epistemological attitude that, in his view, underlies the knowledge of nature. In its many determinations, nature includes minerals, celestial bodies and demons, particulars which can affect other things which are intelligible to human knowledge. The causes of certain phenomena are however hidden, since nature playfully puts obstacles between knowledge and the truth of things. According to Cardano, through one quality, very similar to the lynx's eye (as in the Lyncean metaphor), we can go beyond the obstacle and penetrate the secrets of nature. This quality Cardano calls subtilitas.

Subtilitas is practised in the world of particular things. By scrutinizing the particular, it tries to discover ways that allow our reasoning powers to intervene. Reason's task is to find out the rationes, more or less certain, in the structure of phenomena.

Cardano's efforts, in his attempt at analyzing the meaning of contingent events, are not intended simply as the starting point for his thinking on the value of personal experience in knowledge, but are projected towards the search for a ratio in nature. This ratio is expressed in the form of laws, even if only probable ones, that allow us to make forecasts (e.g. prognosis in medicine, and prognostics in astrology).

His cosmology is mainly that of natural magic, that conceives the chain of being as running unbrokenly between the microcosm and the heavens, establishing a causal correspondence with it. But Cardano's emphasis is more on the natural than on magic; he believes that the stars are the natural instrument through which the divine forces act on the world. Astrology, an ancient art constructed through the memory of observations of regular occurrences, becomes in Cardano's eyes a sort of rational science of natural phenomena. The same thing happens for other disciplines where the subtilitas is practised in the world of particulars. Careful observations and subtle reasonings, carried out personally or by others, are for Cardano the essential empirical sources for the "prognosis". It is in this interpretative direction that we may read his pioneering preference for Hippocrates' works, and especially for the- Epidemia, which in Hippocrates' corpus provides the largest number of specific clinical cases; and we may read his adherence to Vesalius' anatomical researches, a sublime example of expert skill in the practice of subtilitas, as well as Encomium -Neroni, his text on ancient history, in the same way.

Here and there in her book Siraisi seems to distinguish between personal experience and reference to the autoritas, as in the case of the Epidemia. A long chapter, for example, is devoted to establishing whether Cardano had personally carried out human anatomies. But Cardano's concern seems to be that of a "philosopher" who is trying to give an adequate theoretical status to empirical evidence, classically considered to be too uncertain. Cardano seems to be aware, as Bacon will be later, that the mission of empirical and experimental knowledge cannot be absolved by one man alone and that it is necessary for experience to have its authorities, which is why even in his philological readings of the classics of medicine he tries to choose the credible and discard the fabulous.

It would perhaps be useful to reflect further on the worth of his mathematical writings, apparently so different from his medicine, but in fact on a methodological reading of his work closely related. That Cardano wrote a treatise on probability in gambling should not remain a curiosity for historians of mathematics, interested in finding a forerunner for the thinking of Pascal and Fermat a century later. Jan Haking, in his The Emergence of Probability-, -had already in 1975 found the "pre-history" of modern probability in those "experimental" disciplines like medicine or alchemy, which had always tried to find regularity in changing matter. There is a theme here which runs right through Cardano's work, on the surface so heterogeneous, i.e. the idea that the world of things, which expresses itself through signs (symptoms of sickness, physical changes, celestial phenomena, the dreams of the soul, human actions, or the sides of a dice), have a ratio.

If the historians were to pay more attention not just to the bizarre contents of Cardano's cosmology, but also his methodology, his eclectic work would gain in unity. It is a single effort going in one direction: to give status to, and understand the limits of, experiential knowledge, on which are founded all the arts and the moral disciplines from historia rerum gestarum to historia naturalis.

Address: Michelangelo Ferraro, CIS, University of Bologna, via Zamboni 31, I-40126 Bologna. E-mail: