Since 2014, high contracting parties to the CCW have expressed interest and concern about the meaningful human control of weapons systems. There is an extensive scientific and engineering literature on the dynamics of human-machine interaction and human supervisory control of machinery. A short guide is presented here consisting of two parts. Part 1 is a simple primer on the psychology of human reasoning. Part 2 outlines different levels for the control of weapons systems, adapted from human machine interaction research, and discusses them in terms of the properties of human reasoning.