The Invisible World: Early Modern Philosophy and the Invention of the Microscope (review)

Historians of scientific instruments and philosophers of science have long pointed to the development of new kinds of scientific instruments as a fundamental component of the scientific revolution. New and improved instruments, they argue, stimulated the construction of challenging new paradigms that forced the outworn Aristotelian and Ptolemaic ones to the background. Who would have endorsed Copernicanism without the development and refinement of the telescope and without Galileo’s use of telescopic evidence to support the new theory? More than a decade ago, two sociologists of science reopened the subject of the relations between scientific instruments and scientific theory. When Steven Shapin and Simon Schaffer studied the theoretical disputes about the vacuum and the weight of air that preoccupied natural philosophers in the 1660s, they demonstrated that those debates were highly dependent on the construction of air pumps and the replication of experiments before groups of observers. Continuing this line of inquiry about the relationship between instruments and theory in the early modern period, Catherine Wilson, a philosopher by training, examines the fate of a third important scientific instrument, the microscope, and asks what theoretical and philosophical impacts the work of early microscopists had between 1620 and 1720.

Wilson demonstrates that the fervent hope of scientists and philosophers that the microscope would reveal the ultimate constituents of matter and the mechanics of fine, invisible structures of the natural world remained unfulfilled. The enormous enthusiasm that the microscopists of the mid-seventeenth century—Hooke, Leeuwenhoek, Swammerdam, Grew, and Malpighi—brought to their work had faded significantly by the turn of the century. Despite extracting significant new knowledge about insect metamorphosis, plant anatomy, crystallography, the structure of capillaries, and the textures of glands, and despite the discovery of infusoria, human sperm, and numerous other biological forms invisible to the naked eye, there remained considerable skepticism and disappointment about the knowledge produced as a direct result of this new scientific instrument. Why, Wilson asks, did the microscope or, more properly, the images it produced fail to provide philosophically satisfying answers to learned men of the seventeenth century? Do the technical limitations of the early microscopes explain this failure? Do the instruments themselves—or their inherent problems and limitations—provide the explanation? Wilson argues no. Far more was at stake than lenses, focus fields, mounting specimens, perfecting techniques for staining specimens with natural dyes, and the optical quality of the early instruments.

Wilson’s answer lies in epistemology. Willing to concede that early modern microscopists did make positive achievements in describing the subvisible world of nature, she insists that early modern audiences nevertheless regarded such contributions to knowledge as necessarily limited. Far from opening up the hidden truth of the natural world, the instrument-mediated images created by the microscope merely replaced representations of the visible world with a new set of representations of the subvisible world. A visual image was not, and is not, she suggests, perceived as epistemologically equal to reality. The Cartesian ideal of clear, distinct, and immediately perceptible knowledge never emerged; the bold hope of the empiricists that the microscope would extend knowledge that was gained through vision gradually dissipated with the epistemological recognition that appearances were fundamentally different from realities. Hence both Locke and Berkeley, for different reasons, came to reject the contributions of the instrument; the former found them worthless, the latter misleading. Even Leeuwenhoek became despondent of ever discovering—or seeing—the fine organic structures responsible for the generation of living forms.

As evidence for her argument, Wilson adduces the published writings of the early microscopists. She conveys clearly how fragile was the institutional and intellectual unity binding together the users of these instruments. Historians of medicine will be interested in her examination of the microscopists’ arguments over animate contagion (ch. 4). She also scrutinizes the well-known debates over preformation and preexistence (ch. 5). In examining the reactions of philosophers and nonscientists to...