Full Idea
We can distinguish rational exclusivism (all activity is guided by reason - Plato and Spinoza), rational hegemonism (all action is dominated by reason), and rational instrumentalism (reason assesses means rather than ends - Hume).
Gist of Idea
Either all action is rational, or reason dominates, or reason is only concerned with means
Source
John Cottingham (Reason, Emotions and Good Life [2000])
A Reaction
The idea that reason is the only cause of actions seems deeply implausible, but I strongly resist Hume's instrumental approach. Action without desire is not a contradiction.