Any higher mental function necessarily goes through an external stage in its development because it is initially a social function. This is the center of the whole problem of internal and external behavior.... When we speak of a process, ``external'' means ``social.'' Any higher mental function was external because it was social at some point before becoming an internal, truly mental function. It was first a social relation between two people. [quotation on p. 283 of Cognition in the Wild, ellipses in Hutchins]
Now, one of the duties of a pious intellectual posterity is to pass over the really flagrant goofs of our ancestors in decorous silence. Hutchins has signally failed in this duty here: the passage is one of those which make one want to ask, ``Lev Semenovich, what on Earth were you thinking?'' It's a mere unsupported, if heartfelt, assertion; nothing backs it up. It conflates ``external'' with ``social.'' Marking a trail with peebles, or counting on one's fingers, is (if you will) external cognition; but not social. There are things which Vygotsky certainly regarded as ``higher mental functions'' (for instance, face recognition, and object recognition more generally) but which don't even make senses as ``external'' processes, let alone ``social relations between two people.'' (Why just two?) Most basically, one needs a good many internal cognitive widgets just to enter into a ``social relation'' with another person, and these cannot, on pain of infinite and most un-Darwinian regress, have originated from internalizing yet another social process.
Nonetheless, Hutchins's enthusiasm for this notion of Vygotsky's is so great that he merely ``wonders'' whether ``there might be intrapsychological processes that could not be transformations of processes that occured in social interaction. Finding such a process would be a challenge to Vygotsky's position, but unless there are constraints on the possible transformations there is no way to identify such a process'' (p. 285). Just so: there is no way to tell that any internal process ever was an external one, let alone a social one, except by historical evidence that it originated as an external process. Needless to say, Hutchins doesn't examine the historical record of navigation to establish this even for position-fixing, much less ``higher mental functions'' in general, and Vygotsky, on this score, offered no more than hand-waving. (One suspect it's things like this which drove Vygotsky's best students to study brain damage.)