Neuroscientists claim that thoughts and intentions result only from brain activity. It is illustrated by the ability to control a robotic arm only by thought. However although they have a biological support, emotions, ideas and intentions are perceived at another level of reality than synapses and neurotransmitters. The reduction of mind to brain (called monism) represents a categorical error. Psychiatric praxis relies on a dualistic (complementary) position regarding e.g. depression treatment. Antidepressants and psychotherapy have distinct impacts on cerebral metabolism measured by fMRI and different ways to modify emotions. The combination of these two therapies is indicated in case of severe depression.