If there were any doubt about his position on human liberty, Ralph Cudworth puts it to rest in the very first sentence of A Treatise of Freewill: 1 We seem clearly to be led by the instincts of nature to think that there is something ἐφ᾿ ἡμῖν in nostra potestate, in our own power (though dependently upon God Almighty), and that we are not altogether passive in our actings, nor determined by inevitable necessity in whatsoever we do. (4978, 1/TFW, 155) 2Cudworth believes that the instincts of nature are correct. 3 In his manuscript writings on freewill (most of which remain unpublished), he defends their suggestions by arguing against various forms of "fatalism" that would undermine human liberty by rendering our actions the necessary effects of causes beyond our control. For Cudworth, human liberty (the kind of liberty requisite for responsibility) 4 requires that our actions be in our own power 5 in a robust sense that entails the power 1 Cudworth belongs to a group of seventeenth-century philosophers often called the "Cambridge Platonists". For an introduction to Cambridge Platonism, see Hutton (2015, 136-159). The best general overview of Cudworth's philosophy remains Passmore (1951). The best overview of Cudworth's psychology in particular is Hutton (2017). 2 Cudworth produced five manuscripts on the topic of freewill, British Library Additional Manuscripts 4978-4982, hereafter cited in the text by manuscript number followed by page number. Since 4982 is composed of three distinct manuscripts that have been bound together, I distinguish these sections as "4982 (I)", "4982 (II)", and "4982 (III)", followed by page number (using continuous pagination). While most of the manuscripts remain unpublished, 4978 was published in 1838 as A