The article examines epistemological and ontological underpinnings of reasearch performed by means of magnetic resonance imaging and functional magnetic resonance imaging. It takes as its guiding line the important distinction between instruments and apparatuses drawn by Rom Harré. According to Harré, instruments such as barometers or thermometers do not cause the states they measure into existence. Apparatuses, in contradistinction, cause material states into existence to begin with, whereby theses states are subsequently processed according to suitable methods. Thus, when the objects (...) of examination are subjected to 2 or more Tesla in fMRI, a strength of magnetic field never occuring in earthly nature, technical means literally create the states to be examined. Close examination of the functioning of MRI and fMRI indicates that brain states, e.g., are not simply read, or perceived as degrees of temperature are read on scale. Hence, one does not see any mental funtion when looking at fMRI outputs, for the visible output has been semantically processed on the basis of invisible quantum mechanical processes that have undergone translations into digital data caused by the fMRI device itself. (shrink)