What did it mean to experiment with animals in the seventeenth century? There is much ambiguity surrounding the terms “demonstration,” “experience,” and “experiment” in this period, further complicated by linguistic ambiguity: “expérience” in French and “experientia” in Latin could mean what we know in modern English as either experience or experiment. The medieval term “experimentum” referred to the empirical knowledge of a single thing, usually a medical cure. Early modern definitions of experiment and the experimental method are many and various. Observation and direct empirical experience of nature, rather than specific techniques or an overall method, dominate early modern accounts of experiments and experimenting. Such observation could be random or controlled.
Francis Bacon viewed experimentation as a method of forcing nature to reveal her secrets, one aspect of the collection of facts – the natural history – that would then fulfill his inductive method of reaching knowledge. Galileo famously referred to an experiment as a question put before nature, using the phrase “facere periculum,” “to put to the test.” In his published works he emphasized measurement and precision, an exact correspondence between mathematical theory and experimental result. But the precise agreement between theory and demonstration that Galileo wished to claim did not correspond to his actual experimental results, which were much more ambiguous.
Indeed, one can argue that in the Discorsi in particular, Galileo attempted to figure out just what an experiment was. Domenico Bertoloni Meli points out, “Without a canon or even shared views on experimental error . . . different practitioners could have seen, and indeed did see, the same experimental data either confirming or refuting a theory.” These difficulties were compounded in dissection, when it was difficult even to confirm what one could see.
Thus, the very definition of experimenting in the seventeenth century was in flux, and practitioners employed what they termed experiments in differing ways. Descartes, for example, did not clearly distinguish putting to the test from other varieties of experience. While the role of “expérience” in Descartes’s natural philosophy has been much debated, he recorded a great number of observations and interventions, including many dissections. Robert Boyle emphasized the predictive quality of experiments as their main purpose in his definition of a hypothesis:
“That it enable a skilful Naturalist to foretell future Phenomena, by their Congruity or Incongruity to it; and especially the Events of such Experiments as are aptly devised to Examine it; as Things that ought or ought not to be Consequent to it.”
Experience, to these men, included human manipulation of physical objects toward a particular goal (which could be demonstrative, predictive, or rhetorical), but also included simple observation of the ordinary course of nature without manipulation, such as commonly occurred in the natural history of plants and animals. In contrast, most modern experiments involve foresight, planning, and the prediction of an outcome (the hypothesis) and entail active intervention in natural processes, not simply passive observation, although there are experiments that are primarily exploratory.
The natural history of animals cannot be separated from anatomical practice.
By this definition, anatomy and natural history are mainly descriptive rather than experimental practices. However, seventeenth-century men did not clearly distinguish either experiment from experience, or the dissection of dead bodies from that of living animals, further complicating explanations of what constituted experimentation in this period.
The natural history of animals cannot be separated from anatomical practice. Naturalists routinely dissected and at times vivisected the animals they observed; and anatomists routinely employed the descriptive tropes of natural history. The intertwined practices of anatomy and natural history hinged on the distinction between historia and scientia. In Scholastic philosophy, historia referred to a description that did not offer causes, a demonstratio quia (“demonstration of which”) as opposed to a demonstratio propter quid (“demonstration on account of which”). True knowledge, or scientia, included knowledge of final causes, the propter quid.
In anatomical studies, the facts of historia derived from autopsia, meaning “to see with one’s own eyes.” Autopsia, according to the French anatomist André du Laurens, included the dissection of dead humans and “of animals both dead and alive, to observe the motion of the internal parts.” Contemporaries often defined dissection as experimental: an active intervention to reveal the body. Francis Bacon’s New Atlantis included animals reserved for experimental purposes, for “dissections and trials” as well as for experiments in generation and regeneration. In 1681, almost a century after du Laurens wrote, the Cartesian Bernard Lamy equated dissection with experimentation: “To look for the facts of nature, that is to make experiments; for example, the dissections of animals, plants, fish, to open the nature that has been closed to us up to now.”
Among modern historians, Peter Dear has offered the most detailed definition of early modern experimentation. Dear defines an experiment in terms of singularity and contrivance, and linguistically, as a historical account of a particular event. He distinguishes experimentation as an event outside the ordinary course of nature from more generalized experience or demonstration, which displays nature without contrivance. This distinction of experience from experiment might be framed as a distinction between natural history and experimentation as different ways of gaining knowledge of nature.
Like the chymists’ use of fire, the dissector’s knife permanently transformed the body it touched.
But if activity that could be called experimental was rare among naturalists who observed plants, it was commonplace among those who observed animals. Viewing natural history and dissection as distinct activities fails to capture anatomical practices that were at once experimental and descriptive, and fails to capture the practice of the natural history of animals, which most often included dissection. Following Dear’s definition, although dissection involves planning and contrivance, and intervenes in the body to display a nature that is ordinarily not visible, it is not necessarily experimental as opposed to merely demonstrative or didactic, which conforms to a definition of early modern natural history as a descriptive and didactic activity offered by Brian Ogilvie. Simply revealing to sight what had been hidden should not be a singular event. But often it was. Variations abounded among animals and between animals and humans, not to mention among degrees of human skill in performing the dissection.
William Harvey commented that he never dissected an animal without finding something new and unexpected. Dissection was complex and difficult, and dependent on many contingencies of time, place, subject, light, instruments, and skill, to name only the most obvious. In addition, it could only reveal information by destroying its subject; like the chymists’ use of fire, the dissector’s knife permanently transformed the body it touched. The violence inherent in dissection, especially of live animals, was a factor in the acceptance of the knowledge it produced.
Without question, the dissection of live animals was indeed experimental in Dear’s sense. This kind of dissection could reveal functions as well as forms, and always acted outside the ordinary course of nature. The Roman medical writer Celsus had described the resulting condition as “preternatural,” a term much employed in the seventeenth century, meaning exactly this: not supernatural, which only God could cause, but outside the everyday actions of the natural world. In addition, practitioners found the results of the dissection of live animals to be even less predictable than those of dissection of dead animals, varying from species to species and even from individual to individual. The joining of anatomical demonstration with the dissection of live animals, and the validation of historia as a method that created knowledge and did not simply describe experience, made anatomical knowledge into science in the seventeenth century.
This new practice of anatomy depended on animals for both practical and symbolic reasons. Anatomists could easily acquire the domestic animals such as dogs, cats, and pigs that they commonly used. In many respects, they resembled humans enough to demonstrate human function, and when they differed, the differences were also instructive. When the teaching of anatomy revived in the West in the twelfth century, the first demonstration subjects were animals. The humanist physicians of the sixteenth century knew that both Aristotle and Galen had relied upon the structure of animals in order to talk about the human body, and the humanist conception of knowledge as an interconnected whole supported this idea.
Human superiority was based on the possession of reason, which implied the existence of an immortal soul. Since animals clearly lacked reason, they also lacked souls.
Caspar Bauhin asserted in the dedication to his Theatrum anatomicum (1605) that man was “animal admirandum” and the proper subject for natural philosophy, much as Shakespeare at about the same time referred to man as “the paragon of Animals.” The language of the Theatrum anatomicum displays frequent slippage from “human” to “animal,” repeating the phrase “as it is in other animals” (quam fit in aliis animalibus), where “animal” encompasses both animal and human, though Bauhin referred to animals alone as “brutes”.
Seventy-five years later, the anatomist Guillaume Lamy likewise referred to “l’homme ou les autres animaux” as interchangeable, and it was this assumption that provided the basis of much of the interrogation into the nature of life in the seventeenth century. When Galen’s On Anatomical Procedures became part of the humanist harvest of lost classical texts, it further encouraged the ongoing use of animals. Galen’s dissections of living and dead animals provided the basis for his discussion of the human body. Although Vesalius criticized some of his conclusions and their basis in animal anatomy, anatomists from the sixteenth century onward followed Galen in using animals as proxies for humans in anatomical teaching and public demonstration, as well as in private dissections.
The similarity of animal (especially mammal) and human form confirmed an overall divine plan of nature that was for human benefit. That animals did not have souls and therefore could not participate in the afterlife had been established by Thomas Aquinas in the thirteenth century. Accepting Aristotle’s hierarchical concept of nature as a chain of being, Thomas explained in the Summa theologica that human superiority was based on the possession of reason, which implied the existence of an immortal soul. Since animals clearly lacked reason, they also lacked souls. Therefore, humans had no moral obligations to animals, although a good Christian, being compassionate, would not be unnecessarily cruel to animals. Descartes’s “animal machine” brought this notion to a logical conclusion. But questions nonetheless remained about animal consciousness and capacity for suffering, and these arose with particular intensity in the seventeenth century as animals became common experimental subjects.
Reprinted with permission from The Courtiers’ Anatomists: Animals and Humans in Louis XIV’s Paris by Anita Guerrini, published by the University of Chicago Press.
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