That Nothing Is Known
That Nothing Is Known (Latin: Quod nihil scitur) is a 1581 book by the philosopher Francisco Sanches. His most important work, it is a classic of skepticism that criticizes the Aristotelian theory of knowledge. Sanches begins by declaring that he does not even know that he knows nothing, then examines the Aristotelian view that science consists of certain knowledge gained by demonstrations from true definitions. He argues that such definitions do not exist, since all definitions are simply arbitrary names of things. The Aristotelian theory of demonstrations is useless, since in syllogistic reasoning the conclusion must be part of the evidence for the premises (for example, it would be necessary to know that Socrates is mortal in order to know that all men are mortal). Anything could be proven by syllogistic reasoning if one chooses the right premises, and this cannot be real knowledge. Nor can anything be known through its causes, since it would also be necessary to know the causes of the causes, and then their causes, in an infinite regress.
Sanches also attacks the Platonic theory of knowledge, arguing that mathematical knowledge is about ideal rather than real objects. Mathematics is seen by Sanches as having hypothetical status only, since its relevance to experience is not known. True science would consist of perfect knowledge of a thing, in which each particular would be understood in and by itself, but such knowledge can be attained only by God. Humans cannot study objects one by one, since they are all interrelated and interconnected, and their faculties are not reliable enough for the purpose. This being the case, humans cannot attain genuine knowledge. It is possible, however, to use "scientific method" (the term was introduced by Sanches) to gather careful empirical information and make cautious judgments about it.
- The book begins with these words: "Nec unum hoc scio, me nihil scire: Conjecto tamen nec me, nec alios." [I do not know even this, that I know nothing: yet I deduce, neither me, nor others.] (Trans. Keir Douglas Elam.)