Very often, mind is contrasted with the physical world and with the external world. Mind seems to constitute some kind of non-physical internal world. In relation with that contrast, the notion of mind involves three important problems: 1) a serious problem of localization (Where is the mind located?), 2) a serious problem of connection (How does the mind connect with the physical world and with the external world?), and 3) a serious problem of epistemic access (How can we come to know something about our own mind? How can we come to know something about other minds?).

There are three crucial aspects of the mind: intentionality, qualitative character and personal identity. Intentionality is what makes possible that the mind is related with objects and states of actual or possible affairs. Intentionality is exhibited in propositional attitudes, mental states –beliefs, desires, memories, etc.- with a semantic content able to represent objects and states of affairs. Qualitative character is a peculiar quality or phenomenological feature. It is manifest in mental states with a content full of experiential ingredients. Finally, personal identity makes reference to our enduring existence as persons with a “self”, or an “ego”. The three aspects entail very hard problems, both scientific and philosophical.

We need to make reference to another field of problems. The mind can be considered: a substance, a set of properties or attributes, or the result of quite a peculiar sort of description. The realistic compromises of the first option are stronger that those of the second option, and these ones are stronger than those of the third one. The first option is the one of Platon and Descartes, a dualism of substances –the mind as a different substance than the physical, material or extensive substance. The second option is maintained by Aristotle and by many contemporary authors. The third option is favoured by eliminativism. According to eliminativism, the mind would not have an objective reality with independence of a certain way of describing and interpreting some sorts of phenomena, including here a certain way of describing and interpreting some phenomena having to do with our own body and our behaviour.

The last point worthy of mention is that perhaps we would not have to speak of “the mind” in general, but of different “kinds of minds”. There could be purely semantic, conceptual, or cognitive minds in contrast with other much more qualitative, non-conceptual, or experiential minds. There could be natural and artificial minds. There could be very simple minds and very sophisticated minds. There could be human minds and non-human minds, etc.