A common trope in philosophy text books is the supposed battle between rationalists and empiricists, in which the first wanted to base all knowledge on reason and the latter on experience and which was finally solved by Kant who discovered that knowledge was based on both reason and experience. It takes no great historian to discover that this simple tale of two battling schools with three great names on both sides is largely fictitious, not least because e.g. Leibniz did not form a common school with Descartes and Spinoza, but opposed the two in some issues even more than he opposed Locke, the only empiricist of note to have written at the time.
I am not sure who actually invented the fable of the two schools of philosophy, but the first signs of it is the already familiar Kantian tale of Locke as the intuitionist and Leibniz as the intellectualist and Kant himself as the necessary symbiosis of the two. But even after Kant this paradigm was not a given when interpreting the history of philosophy. For instance, Hegel distinguished empiricism from metaphysical school, which apparently included, in addition to the traditional rationalists, ancient philosophers like Plato and Aristotle. Even the separating principle of the two schools is not the same as in the separation of rationalists and empiricists. Metaphysical school, says Hegel, based science on common experiences and analysis of these experiences, while empiricists tried to base it on individual perceptions and then noted that no science of necessities and universalities could be based on them – this description fits not Locke, the paradigm empiricist, but characterises at most a caricature of Humean philosophy. Furthermore, Kantian philosophy is for Hegel not a symbiotic combination of the two schools, but more like a modification of empiricism in the sense that both disagree with metaphysical school about the possibility of certain kinds of knowledge.
In place of a strict division of two schools, various premodern philosophers form then more of a continuum of different standpoints from, say, Spinozan axiomatics as the ultimate in rationalism to Humean bundle of impressions without any necessary connection as the ultimate in empiricism. What I would now like to do is to see where in this continuum Wolff's philosophy fits in. One would expect that Wolff as the supposed follower of Leibniz would be closer to the rationalist end of the line. Yet, Wolff is distinctly aware that many sciences can be based only on experiences. Indeed, in addition to the method of syllogistic reasoning, Wolff tries to describe, however crudely, a method of experimentation, by which basic propositions could be discovered.
Wolff defines experience as something that can be known through perception. Note that he does not identify experience with perceptions. Instead, experience is in a sense more stable than a perception: while a perception might vary from one person to another, experiences are only such perceptions that we know to be capable of being at least in principle communicable to other persons. Thus, experiences are essentially intersubjective.
Despite this stability, experiences deal still only with individual things and might even be deceptional, because human perceptions are not always reliable. Yet, Wolff admits that true universal propositions could be based on experiences. The method for this universalisation is careful experimentation: one varies the situation and so tries to determine the conditions in which the experienced phenomena appears.
Wolff's methodoloy of experiences appears surprisingly empiricist. Still, he is not a pure-bred Lockean, although he does mention latter's work favourably at the beginning of his logic. Wolff does accept also the possibility of substantial knowledge being based on self-evident or analytic axioms, as we already saw in his treatment of mathematics. In other words, analytical propositions are not empty or tautologies according to Wolff. Wolff's justification of the substantiality of such propositions is characteristically pragmatic and even pragmatist. An axiom or a definition can be informative, because it might help us to determine postulates, that is, self-evident ways to affect things. Thus, because we know what a circle is, we know also how to produce one, if suitable materials are given. Even logic is not for Wolff a mere formal system but a helpful tool as a methodology of science.