Deleuze’s version of speculative philosophy is the procedure of counter-effectuation or counter-actualization. In defiance of the causal laws of an actual situation, speculation experiments with the quasi-causal intensities capable of bringing about effects that have their own retro-active power. This is its political import. Leibniz already argued that all things are effects or consequences, even though they do not necessarily have a cause, since the sufficient reason of what exists always lies outside of any actual series and remains virtual. (Leibniz) With the Principle of Sufficient Reason, he thus reinvented the Stoic disjunction between the series of corporeal causes and the series of incorporeal effects. Not because he anticipated the modern bifurcation of given necessary causes (How?) and metaphysically constructed reasons (Why?), but because for him the virtuality of effects is no less real than the interaction of causes. The effect always includes its own cause, since divergent series of events (incompossible worlds) enter into relation with any particular event (in this world), while these interpenetrating series are prior to, and not limited by, actual relations of causality per se. In terms of Deleuze, cause and effect do not share the same temporality. Whereas causes relate to one another in an eternal present (Chronos), effects relate to one another in a past-future purified of the present (Aion). Taken together, these temporalities form the double structure of every event (Logic of Sense). When the night is lit up by a sudden flash of lightning, this is the effect of an intensive, metaphysical becoming that contains its own destiny, integrating a differential potentiality that is irreducible to the physical series of necessary efficient causes that nonetheless participate in it. In order for such a contingent conjugation of events to be actualized (i.e. for effects to influence causes and become individuated in a materially extended state of affairs), however, its impersonal and pre-individual presence must be trusted upon. This takes a speculative investment or amor fati that forms its precursive reason/ground. In Difference and Repetition, Deleuze refers to this will to speculate as the dark precursor which determines the path of a thunderbolt in advance but in reverse, as though intagliated by setting up a communication of difference with difference. It is therefore the differenciator of these differences or in- itself of difference. We find a paradigmatic example of this will to make a difference in William James’ The Will to Believe when he writes: We can and we may, as it were, jump with both feet off the ground into a world of which we trust the other parts to meet our jump and only so can the making of a perfected world of the pluralistic pattern ever take place. Only through our precursive trust in it can it come into being. (James) As Stengers explains, we can and do speculate each time we precursively trust in the possibility of connecting, of entering into a (partial) rapport that cannot be derived from the ground of our current, dominant premises. Or as Deleuze writes: the dark precursor is not the friend (Difference and Repetition) but rather the bad will of a traitor or enemy, since the will does not precede the presubjective cruelty of the event in its involuntariness. At the same time, however, we never jump into a vacuum. We always speculate by the milieu, since a jump in general could never be trusted: If a jump is always situated, it is because its aim is not to escape the ground in order to get access to a higher realm. The jump, connecting this ground, always this ground, with what it was alien to, has the necessity of a response. In other words, the ground must have been given the power to make itself felt as calling for new dimensions. (Stengers) Indeed, if speculative thought cannot be detached from a practical concern, Deleuze at the same time states that [t]here is no other ethic than the amor fati of philosophy. (What is Philosophy?) Speculative reasoning is thus an art of pure expression or efficacy, an art of precipitating events: an art that detects and affirms the possibility of other reasons insisting as so many virtual forces that have not yet had the chance to emerge but whose presence can be trusted upon to make a difference.
In Deleuze’s own terms, there is no such thing as pure reason, only heterogeneous processes of rationalization, of actualizing an irrational potential: There is no metaphysics, but rather a politics of being. (Deleuze) For this reason, the method of speculative philosophy is the method of dramatization. It is a method that distributes events according to a logic that conditions the order of their intelligibility. As such it belongs to what in Difference and Repetition is referred to as the proper order of reasons: differentiation-individuation-dramatisation-differenciation. A book of philosophy, Deleuze famously writes in the preface, should be in part a very particular species of detective novel, in part a kind of science fiction. On the one hand, the creation of concepts cannot be separated from a problematic milieu or stage that matters practically; on the other hand, it seeks to deterritorialize this milieu by speculating on the quasi-causal intensity of its becoming-other.