Wundt is considered as one of the founding father of modern psychology, he founded and directed the first laboratory of psychology at the university of Leipzig, Germany.
The science of mind is defined as the study of psychical processes as phenomena from which it is possible to infer an underlying metaphysical substance, the soul.
The science of inner experience is defined as the study of psychical processes known through introspection, or the inner sense, which is counterposed to outer sense.
Both definitions of psychology are unsatisfactory as they refer to the metaphysical stage of the discipline and promote the idea that psychology deals with a totally different kind of objects than those that can be grasped with outer sense.
The content of consciousness is not known through special organs, but is directly and inseparably connected with the ideas referred to external objects.
Observation, in its proper sense, is the investigation of phenomena without such interference, just as they are naturally presented to the observer in the continuity of experience.
Wundt acknowledges that psychology and natural sciences have different perspectives on the object, but argues that they should use the same methods, advocating for methodological monism.
Experiment is preferred when the object of interest is a natural object, as they do not require to be produced at a particular moment, being relatively constant.
Wundt describes psychic processes with metaphors, particularly with the optical system: fixation point of consciousness: contents of consciousness upon which attention is focused, field of conscious: the whole content of consciousness at any given time.
The study of natural processes linked to the normal development of an organ entails to focus on phenomena “in the making” and requires experiments to analyse and elicit these phenomena under the experimenter’s control.
There are psychical objects which are permanent over time, they thought undergo processes of evolution, but they maintain the same features for a long period of time.
Individual psychology, which deals with the content of consciousness, is all about experimentation as there are no permanent objects in the individual domain.
Experiments are necessary in psychology to investigate mental processes as they happen all the time and can’t be observed naturally repeating themselves with the same subjective state.
The experience is unitary but can be adopted different perspectives/points of view from which we take up the consideration and scientific treatment of a unitary experience.
Every concrete experience can be divided into two factors: a content, what is presented to us, and our apprehension of the content, which deals with the experiencing subject.
The distinction of natural sciences and psychology is based on these two notions: the objects of experience are considered as independent in the direction of natural sciences, while in the direction of psychology the whole content of experience is investigated.