“While ethics is an essential branch of philosophy that deals with character, behavior, and institutional practices, it is sometimes treated as a synonym for ‘morality’. However, inspired by Spinoza, who asked why people stubbornly fight for their own servitude as
if it were their salvation (see Preface of the Theologico-Political Treatise), Deleuze makes an important distinction along those lines: on the one hand, morality involves imperatives that are often grounded in a transcendental (that is, inaccessible) law that people may blindly follow, and on the other hand, ethics involves capacity or power. In other words, morality asks what people should do, while ethics asks what people can do. Although this version of ethics might sound dangerous, it is important to note that ‘power’ is not meant in the Hobbesian sense: whereas Hobbes famously asserted that the exercise of our power in a state of nature involves a permanent state of war, where we all have a right to everything, and also that we ought to give up our power to live in peace, Spinoza, by contrast, argued that we have less power in a state of nature, not more (Deleuze remarks that it is a state of ‘impotence and slavery’ where we are subjected to external causes that we cannot comprehend). Spinoza’s conclusion in the Ethics is that because people are the most ‘useful’ thing in nature to other people, we ought to endeavor to form relations with them (provided that they too recognize this and live ethically through active affects, or adequate ideas). Thus, society may form a system of rewards and punishments for those who are enslaved to passions, but the incentive for entering into it is that other people enable us to exercise our capacity or power more so than we could in a ‘state of nature’.
This notion of ethics becomes somewhat transformed in Deleuze’s reading of Nietzsche’s work, especially with regard to the eternal return. In this case, Deleuze emphasizes that while the eternal return may be a cosmological and speculative notion, its consequences are actually extremely practical. For example, Nietzsche’s famous parable of the demon who asks whether you would want to re-live this life ‘innumerable times again’, could be considered as a curse or as a blessing: a curse (and a ‘weight’), if you think that your life ought to be a certain way, and resent circumstances that you think should have been otherwise; however, it is a blessing if you affirm that there is no particular desirable outcome, that all circumstances must ‘return’ and be affirmed (as in the case with Spinoza, it is a question of your capacity to endure and affirm all possibilities). The answer to the demon’s riddle is perhaps, from this Deleuzian perspective, that the only desirable life is one that incorporates ‘chance’ (that affirms all possibilities, or all outcomes of the ‘dice throw’); any life whose outcomes are determined in advance is denying the eternal return of all outcomes. In this case, our affective disposition is central to a conception of ethics (as in Spinoza), in terms of a capacity or power, but the emphasis is on the necessity of chance as the condition of novelty and joy (it is a ‘tragic thought’, where pain is essentially ‘transmuted’ into joy), in distinction from the Spinozist correlation of chance with confusion, sadness, and powerlessness.”
(La entrada “Ética” en The Deleuze and Guattari Dictionary por Eugene B. Young, Gary Genosko y Janell Watson).