Notes on:   Iris van der Tuin (2019). ‘Deleuze and Diffraction.’ Posthuman Ecologies: Complexity and Process after Deleuze. Eds. Rosi Braidotti and Simone Bignall. London: Rowman and Littlefield International. 17-39. I got the draft on Aacdemia: https://www.academia.edu/38225213/Deleuze_and_Diffraction_2019_ Dave Harris [Very heavy and dense discussion turning on several recent commentaries about Deleuze Bergsoon and Foucault and detailed references to each. So this is only quick] Diffractive reading staves off the dialectic and therefore '"interminable discussion"' (1), of only apparently diverse options, probably tweaked as much by philosophical analysis (Bergson) instead of relying on proper intuition. Nevertheless Bergson does use terms like interference patterns or diffractions as a tool, because experience of this deeper self disturbs the whole consciousness, producing 'a series of waves circling into infinity'. Diffraction also seems exemplary for the new humanities dealing with philosophy, especially for 'transversal methodology'. It features in Deleuze as Plotnitsky has argued, and is an example of people following the implications of quantum theory. P cites W IP which refers to multiple waves controlled by the single wave on the plane of immanence. Methodological implications are less explored. Although it surfaces in terms like the fold or Foucault's points of diffraction [in the Archaeology]. A certain Valentine Moulard-Leonard has written an extensive commentary on Bergson and Deleuze, which is helpful, and suggest that a diffractive methodology might be productive in Deleuze Studies. We can also bring in Foucault via 'feminist implementation and conceptualisation of diffraction'. ML's discussion of an encounter raises the issue of diffraction, although never defines it. It arises with a 'Y-crossing divergence' (4), a forking, found in Deleuze's reading of Proust. ML needs more clarity. Her argument is that Bergson and Deleuze differ in terms of their visions of the world, eg whether it's possible to repair it after World Wars. Deleuze argues that machinism prevents unity. This has methodological implications. Machinism for Deleuze would actually produce both unity and fragmentation, and Bergson probably only splits them as one of those pedagogic pushing of dualisms. Similarly the divergence between Deleuze and Bergson is also traced to the cinema books (here and here) — Bergson sticks with the movement image, but Deleuze's notion of time image is a thorough critique of representational logic, and thus has an 'excess'. Similarly, representational logics in physics can be better understood as 'the direct presentation of time, time as the whole. ML goes on to identify three forms of interference in W IP — 'extrinsic, intrinsic, and non-localisable'(5). However, Deleuze suggests that cinema offers its own intrinsic form of interference as well. ML might have unduly reduced the possibilities here, and a more sympathetic reading of Bergson might point in a different direction. While she's there she notes the implications for OOO, that thingness is implied by the limits of intelligence. However, intuition offers an experience of the whole even before analysis. ML also engages in a futile search for the man Bergson, rather than addressing his thoughts or discussing it as an event. Lambert discusses interference in W IP and says that for Deleuze and Guattari, the brain thinks not the man, that this is a collective form of thought, a plain, with no external point of view. Also the brain is not separate from the world. '"Rather the world is composed of a special type of brain matter"', creating images which become possible. This implies specific modes of interference, Tuin claims. Plotnitsky discusses interference as a concept from physics, distinct from the early reliance on resonance, emerging from AO onwards. Resonance belongs to classical physics, but interference is quantum physics. Resonance is an actualisation, but not the only way to explain how particles become waves through obstruction or amplification. Resonance is an object, but also a concept, an interference which leads to philosophy, or might result from an encounter with philosophy as an engagement. So extrinsic interference is a resonance between two entities related externally, but intrinsic and non-localisable are discussed differently, where concepts are multiple waves, in a quantum physical reality, which helps us understand the plane of eminence as well. Quantum events are 'exemplary non-localisable interferences'. Intrinsic interference might involve implications for art or science from philosophy or vice versa. Plotnitsky therefore identifies phases in the work of Deleuze and Guattari . Barad deliberately diffracts Bohr against Butler as a conscious act, which can be seen as a disruption of extrinsic interference in order to get feminist theory to slide into philosophy, and intrinsic interference. In Barad (2003) she formulates diffraction for the first time, as thinking the social and the scientific together, showing they have no sharp edges, but rather shadows and light, with boundaries that have been enacted — non-localisable interference. Let's discuss Foucault in Archaeology. This is one step back even from W IP. Both Haraway and Barad have an ambiguous stance to philosophy. Quotes from Foucault and Deleuze are epigraphs to the section on individualism and the critique of representationalism, which ontologically separate word and world, and sees subjects as indistinguishable from bodies. Some acts of representation seem unaware of how what is represented gets entangled with discursive processes. Foucault problematises discourses as groups of signs, and Deleuze sees him as wants to go beyond a priori relations. It is this notion of diffraction which has attracted the attention of Deleuze Ian scholars. But we need Barad and Haraway as well if we are to advance feminist new materialism. Barad quotes Foucault as moving beyond discourses as groups of signs or signifying elements to a notion of practices that also form objects, because signs designate things, and therefore an excess is introduced that cannot be reduced to language. Foucault pursues this through the work on strategies, where objects are connected with concepts to produce theories or themes, and eventually discursive formations. However, he recommends we start with points of diffraction of discourse. This is not the same as Bachelard on epistemological breaks. Instead we are looking for 'points of incompatibility'which indicate 'points of equivalence' and link 'points of systematisation'. This will reduce possible options and also allow mutually exclusive '"architectures"' (12). Investigating branching is speculative, but also materialist already, needing no feminist materialisation. Speculation does not mean showing up in endless list of points of diffraction, because we are interested in possible options, processes of 'discrete differentiation'. Foucault might approach Deleuze here. Gutting reads Foucault as indicating forks within discursive formations producing different theoretical turns, permitted by the discursive formation but often not actualised following the work of certain 'authorities,' including relations between discursive formations. These are not disturbing however and can even be seen as formative. Speculation thus precedes material institutional analysis, and preserves possible options that have not materialised. Materialism here doesn't mean naïve realism or representationalism [but more like enactment], operating with thresholds which will need to be clarified by future historians. So some texts might indeed be on the threshold of modern culture, but it could have been others. We need to attend both to what is realised or actualised and what remains possible or virtual. Deleuze's commentary makes it clearer although others have read Foucault that way, particularly Simondon who said that Foucault's notion of threshold 'was informed by quantum physics', especially the notion of the quantum whole as non-decomposable, with a threshold between two diversities [particle and wave]. Barad also sees the quantum as something behind all transitions, all becoming, and also sees in Deleuze on the whole and the part. Foucault saw nature as particularly important as signalling a threshold between modern and post-modern philosophy, but we do not need historical ages [Foucault apparently refers to 'thresholds of positivity, epistemologisation, scientificity and formalisation']. Discourses have their own thresholds. There is no single transition to science. Foucault shares with Bergson the idea of the limits of science as featuring linear time and thus leaving us unable to understand the past. Deleuze's book on Foucault also suggests that he opens up words and things to reveal '"statements and visibilities", which develop into autonomous entities, although they are still linked, not least in '"a blind word and a mute vision"'. Deleuze sees the issue of primacy as central to The Archaeology, but insists this does not mean reduction since it addresses different histories and forms of expression, relating to different statements and forms of visibility, something behind thresholds. What can we make of the threshold of positivity, what Deleuze calls the subject function, although Foucault refers to as individuation and says he cannot yet offer an answer. Interference or diffraction also appears in the discussion of the doing of ethics, aesthetics and politics [talk about sexuality, making paintings, developing political tactics]. Deleuze has a better account of this threshold of positivity. Diffraction also implies a relation between the different options and forkings. Once actualised, enunciations and concepts are incomplete, and new possibilities must be revealed so that possibilities can emerge. This makes diffraction into an event with effects on both sides of the threshold. Deleuze examines the threshold of positivity more explicitly, by looking at subjects and asking, for example how the subject function reveals individuation of different types, including the author. Discourse is at first anonymous. A single statement reveals thresholding. Individuation has a history with specific moments and transformations, but this is a history of statements and visibilities. As soon as they are individuated, we have 'the point of diffraction' (20) an event that is both spatial and durational. Developing that point leads to further warnings not to reduce. AO offers an example of 'complex intra-action' between virtual and actual, closed off [by desiring machines]. The whole itself can be seen as a machine producing all sorts of different sometimes antagonistic movements. There is no single whole to be recaptured, only partial objects, with any totalities still being particular to specific parts, which can be unified, but even this is not a proper totality. It is a multiplicity. This is an improvement on Foucault. We can now return to the idea of diffraction as a forking of options which are all related to each other, not disturbances, but formative. This links back to the issue of disturbance in the Heisenberg Bohr debate in Barad. Again, the philosophical/speculative does not undo the empirical, and objective measurements of wave and particle are both possible, so there is no uncertainty but instead entanglement, an operation that involves apparatus [and she quotes Barad on the stuff about cigars as typically non-reductive]. Lawlor's commentary is also about disjunction and says that diffraction can be absorbed by similarity, even though it actually refers to a disjunction between thinkers or philosophical systems; a point which can disappear in convergence; a deliberate construction by a commentator or philosopher. However, always possibilities indicate that diffraction is a field not the point. So drawing on different parts of an intellectual field will produce a different philosophical system from the one that actually congealed. Even so, Lawlor seems to still operate with a human being constructing these differences or disentangling convergences, althogh he also hints at a concentration of power. However, in any diffraction, there must be a scheme focusing on power and powerlessness, manifested for example in 'a philosophy of interrogation' (26); a set of oppositions, including the possibility that one can turn into the other; and a gradual change. Tuin finds it hard to use these ideas to actually pin down the workings of examples, and Lawlor seems to indicate that his system still lives in excess. There is  a link again with quantum understandings, and the argument resembles Barad on examination of a razor blade revealing complexities on the edges as alternating lines of dark and light. The end of all this could be an argument that competing paradigms often seem to share the same assumptions. Historians have thought should not prejudge but be aware of the difficulties of research, revive the creative thinking of the past, allow for personal subjective factors as well as innate tendencies, recreating forces rather than suggesting new forms of objectivity. Doing intuitive metaphysics in other words, above all avoiding reduction. back to Barad page