Appendix 24. - (295)

Leibniz, to express what he considers innate, sometimes uses the expression virtual knowledge. This would seem to imply that he admitted only knowledge contained in some principle. Consequences are said to be contained virtually in principles because they can be deduced from them. However, a number of passages by our philosopher demonstrate that he accepted all innate cognitions as existing per se, not virtually, in the sense that they were contained in other cognitions. He says, for example:

This shows the difference between Leibniz's virtual knowledge and what this word virtual may seem to mean at first sight. If the sculptor, instead of outlining the statue by using the veins in the marble itself, had only a mechanical rule expressed, say, by some mathematical formula, he would have carved a statue without knowing what the eventual outcome would be. In such a case, he would have virtual knowledge of the statue because the statue is virtually comprised in the rule. In other words, the rule used by the artist has the power to lead him infallibly to the creation of the desired statue, although the statue does not exist in the rule and does not make itself known. The rule and the statue are entirely different things. But this is not how Leibniz understands virtual knowledge which he uses to signify outline knowledge, that is, like the statue designed from the veins in the marble. This is a highly inappropriate analogy which led the great man astray.