In this post doc project I would like to combine a historical with a systematic perspective by investigating the question which influence Newton and Leibniz had on Reid's philosophy of psychology. For there have not been any investigations on this subject matter yet. In particular, I would like to have a look at the following topics: (1) the influence of Newton and Leibniz on Reid's account of the following principles of action: (a) mechanical principles of action, that is, instinct and habit; (b) animal principles of actions, that is, appetites, desires, affections, and passions; and (c) rational principles of action, that is, what is good for us upon the whole, and what appears to be our duty; (2) the influence of Newton and Leibniz on Reid's account of human motivation, (3) on Reid's account of human freedom of will, and (4) on Reid's account of causation. With regard to the outcomes of this post doc project it is to be expected that Newton had a considerable influence on Reid, such that one can find similar positions defended in Reid, whereas Reid's view will be rather opposite to Leibniz's position. For already in his first publication An Essay on Quantity Reid argues in favor of Newton and against Leibniz. Moreover, Reid rather opposes Leibniz's monadology and his concept of pre-established harmony. Quite opposite to it Reid accepts Newton's law of gravity. Therefore it seems plausible to suppose that Reid's philosophy of psychology is mainly influenced by Newton and not by Leibniz.