Winnicott says that the ability to be comfortable when alone is a developmental achievement that arises out of the child’s having played alone in the presence of the mother; the lack of such experience results in being lonely when alone. As with Fromm Reichmann, the emphasis is on the mother having provided a particular experience, rather than the child’s innate fantasy life, that has led to a sense of loneliness. Buchholz building on Winnicott takes issue with those who believe that social isolation is destructive, and focuses on how having time alone can be both nurturing and productive. We believe that pleasure in alone time depends upon a person’s sense of self and others rather than whether the person is alone or in the presence of an other.
The following is an interesting paper on loneliness.