The diploma thesis investigates, against the background of the naturalism debate, the extent to which the phenomenological and ecological concept of the brain that was developed by Thomas Fuchs can be used to defend the assumption that the authorship of ideas is to be attributed to us, as bodily subjects. Exponents of the reductionism movement in brain research declare the brain as the actual subject. Whilst we experience ourselves namely as consciously experiencing and freely acting subjects, this is nothing more than illusions created subsequently by the brain. The work begins with a condensed description of the history of brain research. The second part is dedicated to a discussion of the phenomenological and ecological concept of the brain. In its portrayal, the connections between brain, organism and environment which lead to the description of the brain as the relationship organ are comprehended. The objective of the third part is to clarify whether the illusion thesis according to which our brain is the subject of acting is plausible. The difference between physical behaviour and action, bodily intentionality, self-effectiveness, as well as the various perspectives associated with the taking of action that must be recognized is investigated. As to the connection between human action and the problem of free will and freedom of action, reference is made to classical and modern freedom theories. Based on the phenomenological and ecological theory, a convincing argument can be made that we, as bodily subjects, rightly claim the authorship of our actions. Apart from this basic thesis, it can be shown that it is justified to reject the illusion thesis because of an unclear concept usage and a tendency to mix up natural scientific knowledge with metaphysical interpretations, on the one hand, and to neglect the question of an appropriate method, on the other hand.