Rational Psychology

its difference from empirical [psychology].

...from the empirical branch, [those things which] are present in the soul, or can be present. For Rational Psychology The branch of philosophy that uses reason and logic to explain the soul's nature, as opposed to Empirical Psychology which relies on observation. is that part of philosophy which treats of the soul (§ 58, 112, Preliminary Discourse). Therefore, in this science, we must provide the reason original: "ratio." In Wolffian philosophy, this refers to the "sufficient reason"—the explanation for why something is the way it is and not otherwise. for those things that are either actually present in the soul or have the potential to be present (§ 31, Preliminary Discourse).

We have already pointed out elsewhere (§ 152, Preliminary Discourse) that this is the difference between rational and empirical psychology, and it will become clear from a comparison of the two. Indeed, I have no doubt that a reader who pays serious attention will understand that concerning those things that pertain to the soul, reasons can be provided no less clearly than modern physicists are accustomed to provide concerning material things.

§. 5.

The possibility of rational psychology.

Rational psychology is possible. For in rational psychology, we must provide the reason for those things which are present in the soul, or can be present (§ 4). Now, since the human soul actually exists (§ 20, Empirical Psychology), and is therefore a being original: "ens." A foundational concept meaning anything that is possible and does not contain internal contradictions. (§ 134, Ontology), there are also certain things found within it which are not mutually contradictory, yet are not determined by other things present at the same time, nor by each other (§ 142, Ontology). Consequently, the soul has an essence original: "essentia." The necessary, first internal principle that makes a thing what it is. (§ 14, Ontology), and within that essence is contained the sufficient reason for those things which, besides the essence, are either constantly present in the soul or can be present (§ 167, Ontology). Therefore, rational psychology is possible (§ 91, Ontology).

We add this proposition so that it may be understood that rational psychology, as we define it, is not an empty term (§ 38, Logic), nor is the labor spent in establishing it in vain. Furthermore, it is evident from the very notion of possibility how one must proceed in rational psychology. Specifically, a certain essential concept must be formed, and from it, those things that we establish a posteriori original: "from the latter." Knowledge derived from experience or observation. in empirical psychology must be gathered a priori original: "from the former." Knowledge derived from reason or first principles, independent of specific experience.. This is achieved if we weigh those things which were noted there concerning the soul, and inquire by the power of the distinct notions developed there, which of them can be demonstrated from others. We have certainly used this method while by the power of—