It is no secret that Deleuze's project is in many ways at odds with Kant's. Whereas Kant's transcendental project sought to set forth the conditions of possible experience, Deleuze's transcendental empiricism (and yes, it is a transcendental project) sought to understand the conditions of real experience. In his efforts to develop this project, Deleuze turned heavily to the early modern philosophers, most notably Spinoza, Leibniz, and Hume. There has been an upsurge of excellent work in early modern philosophy, as is well represented on this blog by Eric Schliesser, Dennis Des Chene, and Charles Wolfe. I would argue that one reason for the increased interest in early modern thought converges with Deleuze's project: namely, it's part of an effort to develop realist alternatives to various forms of Kantian transcendental idealism and anti-realism.
As part of this general trend in philosophy it might be time to reconsider the stoics, and in particular Seneca.
There has been some excellent work on Seneca in recent years (there's Brad Inwood's Reading Seneca for example), and John Sellars has written on the relationship between stoicism and Deleuze and on stoicism more generally (in his book The Art of Living). Perhaps Seneca and stoicism could play a contributing and relevant role to the Deleuzian effort to develop a realist alternative to the Kantian project. I have taught Seneca's essay "On Anger" in my political theory classes and have had surprising success with it. There is the tabloid factor in this essay that gets students' attention - the story Seneca shares of the King Cambyses who shot an arrow through the chest of the son of one of his best friends to prove he was not incapacitated by having drunk wine (and then he had the son's chest split open to prove the accuracy of his shot) is a notable example - but there are many other reasons for finding this essay helpful. The most notable reason begins right with Seneca'a acceptance of Aristotle’s definition of anger as being largely his own—namely, it is ‘the burning desire to pay back pain,’ and it is something ‘that wild animals are incapable of.’ For Seneca, however, while Aristotle allows for anger as something that is needful when kept under control, adding that ‘no fight can be won without it,’ Seneca categorically rejects Aristotle’s position as false. ‘If it [anger] listens to reason and follows where led, it is no longer anger, the hallmark of which is willful disobedience.’ So even if Aristotle is right that anger becomes directed towards an opponent in a fight and provides greater resolve as a result, for Seneca it is no longer anger if it is led by reason. It thus appears that for Seneca there is no room for the cohabitation of anger and reason, which in turn anticipates Kant's claim that ‘the inclinations themselves, as sources of needs, are so far from having an absolute worth, so as to make one wish to have them, that it must instead be the universal wish of every rational being to be altogether free from them.’ And yet there is an important difference between Seneca and Kant, and this turns on Seneca's arguments that one does not simply relegate passions such as anger to the side and place oneself under the dictates and imperatives of reason; rather, much of Seneca’s essay is spent providing a number of techniques to employ and perfect as one feels one’s anger rising, or how to deflect the simmering anger one perceives in another such that it doesn’t grow out of control (we can see here that Foucault's interest in the techniques and technologies of the self connects with Seneca, and hence why Foucault was interested in Seneca in his late writings). Seneca, however, does not discount reason or judgment. Far from it. Judgment is a crucial part of what Seneca sees as the ‘greatest remedy for anger,’ which he claims ‘is delay,’ for in delaying you allow judgments to form that may allow you to overcome the anger. Thus judgment is as important for Seneca as it is for Kant. The difference, and this is a difference that makes Seneca’s thought especially relevant to a Deleuzian-inspired project, is the basis upon which we understand these judgments. Is it, as Kant would have it, judgments all the way down, down to the synthetic apriori judgments of the understanding, or is this capacity to judge itself a contingent part of a larger process, and a process that is irreducible to judgment? Seneca, it seems to me, argues for the latter position.