Alberto Vanzo writes…
An interesting aspect of Kant’s use of the rationalism/empiricism distinction (RED) is that he does not only apply it to the moderns, but also to the ancients. Kant portrays Leibniz as an adherent to Plato’s rationalism and Locke as a follower of Aristotle’s empiricism. Could Leibniz’s New Essays be a source of Kant’s distinction between empiricism and rationalism?
Here is one of Leibniz’s comments on his disagreements with Locke in the Preface of the New Essays:
- Our differences are about subjects of some importance. There is the question about whether the soul in itself is completely empty like tablets upon which nothing has been written (tabula rasa), as Aristotle and the author of the Essay [Locke] maintain, and whether everything inscribed on it comes solely from the senses and from experience, or whether the soul contains from the beginning the source of several notions and doctrines, which external objects awaken only on certain occasions, as I believe with Plato and even with the Schoolmen […]
Here, Leibniz pits Plato and himself against Aristotle and Locke with regard to the existence of innate ideas (“several notions…”) and a priori truths (“… and doctrines”). These are precisely the issues around which Kant frames his distinction between empiricists and rationalists (or, as he sometimes calls them, dogmatists and noologists). However, Kant holds that a third issue divides ancient empiricists like Aristotle from ancient rationalists like Plato. It is the existence or inexistence of objects of which we cannot have sensations. According to Kant, ancient rationalists claim that there are non-sensible objects (Platonic ideas). Ancient empiricists, like Aristotle and Epicurus, deny this. Leibniz does not focus on this issue, but Christian Garve (who would later become one of Kant’s early critics) did. Like Kant, Garve divided ancient philosophers into two camps based on whether they admitted substantive a priori truths, innate ideas, and non-sensible objects. He drew this distinction in a dissertation that he published in 1770, eleven years before Kant’s first Critique and five years after Leibniz’s New Essays. Let me summarize Garve’s statements on each of the three points.
A priori knowledge
After they learned to distinguish between appearance and reality and between the senses and the intellect, philosophers took two opposed paths:
- Some [like Heraclitus] devoted themselves to exploring the nature of the senses with great care and they subtly searched in the senses the mark and sign of truth. Others [like Parmenides], having ignored and set aside the senses, devoted themselves entirely to the faculty of intellect and to contemplating with their mind the thoughts that they had gathered in themselves.
This epistemological divide gave rise to an ontological divide:
- [T]hose that sought the foundation of the truth to be discovered in the senses were forced to refer [only] to the things that are subjected to the senses […]; and those claiming that true cognition is distinctive of the mind, not of the senses, denied the name and almost the rank of things […] to sensible items. They ascribed it only to [merely] intelligible things […]
On the one hand, we have Protagoras, Democritus, Epicurus, the Cyrenaics and even the sceptics. On the other hand, we have Plato.
Those who denied “the truth of the senses” did not only have to posit a realm of non-sensible beings. They also had to defend the existence of innate ideas. This is because, if there is no truth in the senses, we cannot derive “true notions” from the senses (where true notions appears to be, in some sense, notions that map onto reality). We must claim that they are “innate in the soul and prior to every sensation”. “And thus were born Plato’s famous ideas, on which he says various, inconsistent things”, like those who are forced to embrace a conclusion, “although they do not understand well enough what it may be or how it could be true”.
Garve does not use the terms “empiricists” and “rationalists”, which would take on their now-common meanings only with Kant. However, the way in which Garve carves the two opposed camps of ancient philosophers maps neatly onto Kant’s distinction between ancient empiricists and rationalists. Garve also suggests that Locke and Berkeley followed Aristotle, whereas Leibniz followed Plato. This is because, in the antiquity, “nearly the whole territory of all opinions which may be held on this matter had been explored; all matter for supposition and invention had been used”.
Kant too thought that modern empiricists and rationalists followed the footsteps of their ancient predecessors. This brief survey of Leibniz’s and Garve’s statements suggests that their historiography of ancient philosophy may have been a source of Kant’s influential distinction between empiricism and rationalism.