Jeannerod, Marc “Are There Limits to the Naturalization of Mental States?"

In “Are There Limits to the Naturalization of Mental States?” Marc Jeannerod brings further neuropsychological research to bear on the topic of intentional action and its role in constituting self-awareness. He notes that humans are social beings, and that communicating with others is a basic feature of human behavior. A long-standing philosophical question is how it is possible for one person to recognize the mental states of others. A key insight here comes from neuroscience: the neural system one uses for detecting intentions of other agents is part of the neural system that generates one’s own intentions. Evidence for this comes from studies with monkeys showing the existence of neuronal populations in several brain areas that selectively encode postures and movements performed by conspecifics. Much of this population of neurons overlaps with those involved in the generation of the monkey’s own movements. This same sort of overlapping of function is suggested by PET-scan studies in humans. When subjects were told to watch an action with the purpose of imitating it, parts of the motor cortex were activated, whereas this was not the case if subjects were told to watch only for the purpose of later recognition.

The research summarized here sheds light on the problem of other minds, but in so doing raises a new philosophical problem: if the intention of another’s action is represented in my neural system by means of the same neural activity as my own intention to act, how does this intention get attributed to the right agent? Jeannerod shows that having a neural representation of an intention and attributing it to myself are two different processes, which are not automatically linked. Jeannerod reports further research that highlights this problem. Experimental situations have been devised in which it is not obvious to the subjects whether they are seeing an image of their own hand or that of the experimenter, moving in response to instructions. When the experimenter’s hand movement departed from the instructions, subjects had no difficulty recognizing it was not their own. But in thirty percent of cases when the experimenter’s hand followed the instructions, normal subjects mistook it for their own. Schizophrenic patients misattributed the experimenter’s movements to themselves eighty percent of the time. This is consistent with clinical reports that schizophrenics suffer from a tendency to incorporate external events into their own experience.

Jeannerod ends his essay with a reflection on the limits of human abilities to know other minds. A person’s individuality resides in the fact that no two individuals ever share all of the same experiences. Thus, no two people’s global neural states will ever be the same. If neuroscientific understanding is based on similar or identical neural representations, then some aspects of personal identity are beyond the realm of scientific inquiry.

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