The Metaphysical Subject as Background to the Early Wittgenstein"s Epistemology

Proposition 4.1121 of the Tractatus states that epistemology
is the philosophy of psychology. What should we take
this to mean? Philosophy, on Tractarian terms, is an
activity by which thoughts are clarified. This activity ranges
from checking terms to see if they have meaning to
investigating a network for its regularity. Epistemology,
then, would be the philosophical analysis and clarification
of any possible psychology, although it is not clear what a
psychology on Tractarian terms would be. Understanding
what such a psychology might be is necessary if we are to
understand better what this epistemology would demand
of us; however, to approach such an understanding, we
will need to attend to the notion of subjectivity at work in
the Tractatus and to the way it is related to thought and
logic.