Dualism may be the fundamental error in Western thought--in our assessment of the universe and our place in it, and therefore in what we do in it. There are problems with viewing the mind as something distinct from the body. The mind becomes a kind of receiver of transmissions from the external world; it is passive. Or a citadel; where we are protected from the world. Or our only access to that which is said to be beyond the universe. Or what sets us apart from the rest of the universe, i.e. those creatures which have the misfortune of being something other than human, and gives us a kind of dominion over it. Sometimes we maintain that our minds are the only means by which we can ascertain what is really true. Sometimes we come to consider our thoughts and feelings as existing apart from the universe--they are private, subjective, relative, they cannot be considered objective.
Perhaps this dualism enters into Eastern thought as well. There seems in some instances to be a desire to detach the mind from the body, not to mention the rest of the world, in pursuit of the ultimate.
For a time, one can "detach" oneself from the "rest of the world" in a certain sense. One can sit motionless and do nothing, or stay in one's room, or meditate, or pray. There may be benefits in doing so in certain cases. But these are peculiarly selfish activities, if one can use that word. They may be dangerous activities in some cases. Chances are excellent that we would in any case act soon enough, as we'll become hungry or thirsty, at least. That damn body keeps interrupting our contemplation, or self-absorption. Worse yet, other people or things do, as well.
The view that the mind is somehow distinct from all else strikes me as puzzling. There doesn't seem to me to be anything particularly dismal about being a living organism which necessarily interacts with its environment and other organisms. It seems quite natural, in fact. Unless, I suppose, one hates the environment with which one must necessarily interact or others which inhabit it. But that is something I think could properly be called unnatural--or at least futile.
This dualism pervades traditional philosophy. The "problems" of the external world and other minds seem to follow from this view as a matter of logic. So, in strangely similar ways, do the views that morality is a matter of absolutes or is completely subjective.
But it seems clear that the mind is not something separate. We act and react. Our thoughts, feelings and desires are not private, as they result from our involvement in the world and have consequences in the world. They don't simply "exist" somewhere in the mind. They are, as Dewey maintains, part of our conduct, part of what we do as living creatures.
The stoics and some of the other ancients realized this as well, I think. It was part of their conception of humanity as a functioning part of the universe, albeit a special part. Those who maintain the stoics were supremely selfish misconstrue them. Recognizing that there are things beyond our control which we should not allow to influence us--especially to dismay us--was a kind of practical wisdom. It wasn't intended to be a means by which we separate ourselves from the universe and our fellow creatures, as it is essential to Stoicism that we honor and respect the universe and others.
Somehow, we came to believe that we are apart from not only the world, but our own bodies. It would be interesting to explore how this happened. Do we blame Plato and other Greek thinkers, because of their view that what can change is inferior? Do we blame religion and its focus on a presumed other world, much more important than this one? Yeats wrote of our neglect of "monuments of unaging intellect." But why assume change, a necessary condition of growth, is inappropriate?
I think it would be useful to rid ourselves of this fantasy. Assume, arguendo, that that we're merely transients in this world, on our way to another, which may be either heaven or hell; assume even that this is the only world. In what sense do either of these views mean that we should not live better lives, and better ourselves and others? The mind is not something unchanging, unmoving, or a mere observer; it's simply a part of us, as we are parts of the universe.