Hume's account of belief has been much reviled, especially considered as an account of what it is to assent to or judge a proposition to be true. In fact, given that he thinks that thoughts about existence can be composed of a single idea, and that relations are just complex ideas, it might be wondered whether he has an account of judgment at all. Nonetheless, Hume was extremely proud of his account of belief, discussing it at length in the Abstract, (...) and developing it in the Appendix. Furthermore, he claimed several times that his account was new. It was not just a new answer to an old question, but an answer to a new question as well. Why did Hume think he was raising, and answering, a new question? Is his answer really so appalling? Why did he define belief in terms of a relationship with a present impression? In this paper, I propose answers to these questions. The answers emerge by contrasting Hume with Locke. Locke thought that belief was a pale imitation of knowledge, and that the assent we give to propositions is constituted in the very same act as forming those propositions. Hume saw the problems such a theory faced concerning existential beliefs. By ceasing to treat existence as a predicate, Hume was confronted with the issue of what it was to judge something to be true, or to assent to something. This issue had to be solved independently of the question of what it was to conceive something, or understand the content of a proposition. Hume thought this problem was new. He should be looked at, not as giving a bad answer to an important question, but rather as being the first in the early modern period to recognize that there was an important question here to be answered. (shrink)

In 1675, Burchard de Volder (1643–1709) was the first professor to introduce the demonstration of experiment into a university physics course and built the Leiden Physics Theatre to accommodate this new pedagogy. When he requested the funds from the university to build the facility, he claimed that the performance of experiments would demonstrate the “truth and certainty” of the postulates of theoretical physics. Such a claim is interesting given de Volder’s lifelong commitment to Cartesian scientia. This chapter will examine de (...) Volder’s views on experiment and show that they are not Newtonian or inductivist, as is sometimes claimed. While de Volder thinks we need deductive reasoning from first principles to provide evidence of the certainty of the content of our physical theories, he also contends that we need experiment to provide evidence of the certainty of the existence of the particular bodies those theories discuss. This approach to experiment is based on a distinction between rational certainty and the certainty of material bodies in the actual world. While this account is deeply influenced by Descartes, it is importantly different than Descartes’ distinction between absolute and moral certainty. De Volder’s “Cartesian Empiricism” is best understood as a continuation and further development of a long tradition of teaching through observation at Leiden. (shrink)