In the Optics, Descartes claims that telescopes and microscopes lead to morally certain knowledge. It is unclear, however, that Descartes’s expressed confidence in these instruments is warranted. In this article, I show how a limited range of telescope and microscope observations could lead to morally certain knowledge for Descartes, and how observations beyond this range admit of enough reasonable doubt to undermine moral certainty. I also explain moral certainty as a form of knowledge in Descartes’s scientific practices, his epistemic commitment (...) to optical instruments, and I offer an explanation for why Descartes never used optical instruments in his scientific endeavours. -/- ---- -/- Dans la Dioptrique, Descartes prétend que les télescopes et les microscopes donnent accès à des connaissances moralement certaines. Cependant, il n’est pas certain que la confiance accordée par Descartes à ces instruments soit justifiée. Dans cet article, je montre comment une gamme limitée d’observations effectuées à l’aide d’instruments d’optique pourraient mener aux connaissances moralement certaines pour Descartes, et comment d’autres observations allant au-delà de cette gamme introduisent suffisamment de doute raisonnable pour saper cette certitude morale. Enfin, j’interprète la certitude morale comme une forme de connaissance dans l’empirisme de Descartes, j’explique son engagement épistémique envers les instruments d’optique, et j’éclaire les raisons pour lesquelles il n’a jamais employé d’instruments d’optique dans ses propres recherches scientifiques. (shrink)

Artificial insemination and other fertilization techniques are today considered central to the history of reproductive medicine. The medical treatment of infertile couples, however, constitutes just a small part of the whole story of artificial fertilization. Lazzaro Spallanzani in particular, said to have been the inventor of artificial insemination, did not develop this method for medical purposes. He belonged to a generation of naturalists to whom artificial insemination was part of a heterogeneous series of investigations that were undertaken to explore the (...) natural history of animal generation. Questions concerning conception, the role of the gametes, the definition of species, the production of hybrids or livestock breeding were all included in these investigations. Thus, no one strain of thought, nor single set of ideas or interests, entirely shaped the development of artificial fertilization. (shrink)