Actions

Is all that we can "directly know" just our sense impressions (input signals)? That is, Lewis' "observational terms", O-terms. Hume said "...only the successive perceptions constitute the mind." (A Treatise on Human Nature, 1739) Asa H does learn just such sequences of sensations.  But for Asa H as well as for humans there are also actions (output signals).  And these are important for optimization/intelligence. Simple observation versus full blown experiment.  In Asa H extrapolations, deductions, etc. serve as hypotheses for future testing and correcting.