Rick Dolphijn and Iris van der Tuin claim that new materialism, as "a cultural theory for the twenty-first century" (110), "is in many ways a wave approaching its crest" (16). Indeed a growing field of contemporary analysis, new materialism's contributions are broad and multidisciplinary, and its responses varied. The authors argue that new materialism, being both an "important but poorly defined force in contemporary academia . . . stands in need of conceptualization" (92). With this text, Dolphijn and van der Tuin set themselves to this task, performing what they term a "mapping" (71) of new materialism that reveals the monist or "immanent" (96) orientations in its rethinking of humanism, dualism, and linear time, with its concomitant possibilities for a transversal and affirmative methodology, or "practical philosophy."
The book is divided into two parts. The first presents a series of interviews with key new materialist scholars Rosi Braidotti, Manuel DeLanda, Karen Barad, and Quentin Meillassoux, and the second serves to both contextualize the content of the interviews as well as to deliver the authors' original contribution to this field. In this undertaking, Dolphijn and van der Tuin provide a cohesive overview of contemporary material philosophies and their genealogies, in which the influences of the Continental tradition as it intersects with science studies and feminism are clearly marked out and engaged.
Given its adoption of the adjective "new," this positioning of a new materialist genealogy is one that deserves, and receives, close attention in Dolphijn and van der Tuin's argument. In its aim to work through "the transcendental and humanist (dualist) traditions that haunt cultural theory" (86), we see a sophisticated temporalizing at work that refuses a straightforward historicity. The authors are careful not to reinstate dialecticism as a response to "the old" (see 89, 94, 97, and 120, for examples). Instead, they underline and develop a new materialist "cartographical" methodology premised on a "non-dualist" (94) rereading of past traditions, one that involves "[r]eworking and eventually breaking through dualism" (97), or "pushing dualism to an extreme" (see chapter 6).
Accordingly, for these authors new materialism does not reject past traditions, nor is it simply a "linear consequence" (116) of responding to a history of materialist thought, but a task of opening up "the paradoxes inherent in these traditions by creating concepts that traverse the fluxes of matter and mind, body and soul, nature and culture . . . " (86). This, as the authors indicate in their introduction, is not an additive approach, but one that "traverses and thereby rewrites" (13) dualist thinking, a traversing that they describe as the "transversality of new materialism," engaged in detail in chapter 5.
The transversality of new materialism is also considered in terms of the way it disturbs the usual (dualist or dialectical) positioning of matter and meaning. Paradigmatically, new materialism questions and shifts "the shared representationalism" of postmodernist constructivism and "modernist scientific materialism" (107; original emphasis) in affirming a radical immanence of these terms (as discussed through the work of DeLanda and Braidotti in chapter 5). In this vein, new materialism does not, as the authors claim, citing Claire Colebrook, commence at one end or another of the "representation/material dichotomy" (108) in the way that modernist and postmodernist paradigms have presumed to do, but affirms matter as "a transformative force in itself, which, in its ongoing change, will not allow any representation to take root" (107; original emphasis). This shifts the status of matter from a primary ontological reality that precedes the properties of language, mind, subjectivity, and representation, to emphasize the relational and (therefore) durational dimensions of materiality in its entangled emergence with these ostensibly transcendent terms or substances. It is the "force" and "movement" (113) through which relations (for example, those of matter and representation) actualize that most fascinates new materialism, according to these authors.
Thus phenomenon for Barad (52), intensive and processual morphogenesis for DeLanda (162), or metamorphosis for Braidotti (107) become processes of materialization, signaling the inventive, autopoietic, and self-organizing force of matter that "is not a substrate or a medium for a flow of desire," as Barad (59) explains, but what Brian Massumi would claim as "ontologically prior" (to mind, for example), without the usual idea of sequence that this would imply (see 172). Following Barad (and Donna Haraway), "mattering" is thus "simultaneously material and representational" (96), it is essentially "material-discursive" or "material-semiotic" (109). On this basis, new materialism does not "discard signification" or entail "a simple move beyond social constructivism in a progressive way" (98), but rather "directs it to its proper place and qualitatively shifts the linguistic turn accordingly (i.e. non-dualistically)" (110).
As its primary focus, the new materialist aim to rethink the relation of matter and ideation as productive of a "morphology of change" (92) is, as the authors point out, a continuation of the feminist project to emancipate matter (93), an aim that makes the question of new materialism's relevance in and for feminism a mainstay of this text. Although a number of feminist arguments form the focus and examples of the authors' analysis of new materialism "put to work" (103), its address to how we might think a specifically feminist historiography, along with sexual difference as a "practical philosophy" (87), is developed more explicitly toward the end of chapter 6 and in detail in chapter 7, where sexual difference is shown to be a sexual differing via an insightful reading of Simone de Beauvoir's The Second Sex.
To get to this point, Dolphijn and van der Tuin turn their attention in chapter 6 to the ways in which new materialism constitutes a philosophy of difference, one built upon an "affirmative" approach that necessarily involves theory-formation as an active and transformative, because ontological, process. Working with Henri Bergson, Gilles Deleuze, and Colebrook, difference is understood in terms of a "univocity" or "ultimate unity" (Deleuze's terms; see 128-30): it is the space and duration through which relation, even negative relation, is made possible. As the authors make clear, this is not to say that difference is the movement that precedes (negative) dualist relation (similar to the way in which matter does not precede representation). Instead, dualism, or any form of relation, is made possible (a virtuality actualizing itself) through a difference that continues to traverse itself. This is difference as self-differentiating, or difference shown differing, spatially and temporally.
This being the case, and in line with feminist reworkings of difference such as Braidotti's project to rethink the equation "different-from is necessarily worth-less-than" (cited on 127), new materialist analysis shifts an understanding of difference from one that is implicitly negative, oppositional, and hierarchical (the "ordinary dualism" to which Bergson refers) to one that is "affirmative--i.e., structured by positivity rather than negativity" (127). In traversing or passing through dualism in the vein of Deleuze (and to an extent, Bergson), dualism is not rejected, but, being pushed to an extreme, is shown to be "inherently untenable" (127).
In keeping with their focus on new materialism's rewriting of modernity, the authors take as their departure point in chapter 7 the idea that a feminist historiography does not simply reflect through a feminist history, but actively creates feminism in the process. This makes feminism more than "a merely reactionary stance" (138). It is a "performative ontology" (87), one that, following Deleuze and Barad (discussed in chapter 6), engages in the activity of "creating concepts, which is an onto-epistemological activity" (126-27). Along these lines, it is with Beauvoir that Dolphijn and van der Tuin perform a rewriting of sexual difference "as a practical philosophy in which difference in itself comes to being" (141; original emphasis).
Their intervention commences with a review of Judith Butler's popular account of Beauvoir's work, in which the authors diagnose a dualism that separates gender as a "form of expression" from "sex as it refers to a form of content" (143), premised on Butler's "oversimplified idea of language" (see 143-45 for their full analysis). The consequence of this is that the word (gender) is projected into the thing (body), ultimately fixing both into place, albeit that their usual sequence (sex defines gender) has been inverted in Butler's design. As they argue, this move restricts feminism's potential by turning it into a "descriptive historicism" (145) that finds the present to be a product of the gendered patterns of the past, and leaves little space to "think the possibility of the new . . . , of thinking a future not bound to the present" (citing Elizabeth Grosz, 144).
Instead of this fixing into place of sex, gender, and linear time, for Dolphijn and van der Tuin The Second Sex "opens the way for the indeterminacy of sexual differing" (142). Here, the key to Beauvoir's work with sexual difference is found in her notion of "flesh." Like Deleuze and Félix Guattari's (Spinoza-inspired) concept of "desire," "flesh" can be conceived of as a nonessentialist understanding of nature that endlessly recreates itself in relation (see 151). This means that categories (such as sexual difference) are not given or essential, nor (as forms of signification) essentially incorrect or nonexistent. They materialize as a process of differing, as "ontogenesis" (147), as the authors suggest. It is by starting with the flesh that sexual difference can now be seen as "material-discursive" (Barad) or an "expression of bodies" (Grosz) (153) in a move that marks Beauvoir's feminism as a distinctively "vitalist project" (149; original emphasis). Importantly, this notion of difference is energized within Beauvoir's argument, not simply delivered via a retrospective reinterpretation of her early-second-wave feminism.
According to Dolphijn and van der Tuin, it is in the conclusion to The Second Sex that Beauvoir's suggestions for a practical philosophy of sexual difference culminate, and in a way that demonstrates the affirmative project that constitutes a new materialist methodology: Beauvoir is said to offer an argument for sexual difference that "implies sexual differing all along" (154). Neither striving toward equality (an equivocity that relies upon predetermined identities) nor fitted to androcentrism, not seeking for or rejecting emancipation in modernist, progressivist, and negatory terms, the authors instead find in Beauvoir's feminist vision (and contrary to its dominant reception) a call for emancipation for women that "speaks the language of difference" (154). This difference constitutes as an "ethics of affirmation" (154) that will not deny, but refuses to enclose women in their relations with men (to paraphrase Beauvoir, as quoted on 154), but that also finds within this sexual difference a sexual differing that marks the possibility for these relations to materialize otherwise. Rather than seeking to resolve this paradox, the new materialist claim for feminism as a performative ontology "entails the affirmation of the fact that feminism materializes" this paradox of sexual difference, "and that feminism has to be understood precisely as such" (142; original emphasis). Crucially, the transversal temporality of difference ensures that it is not in the future alone that sexual differing is realizable. Instead, it can be found in "the linguistic codes of sexual difference where it always already roams, materially and vitally" (156). Thus, pushing sexual difference to an extreme engenders and reveals a sexual differing that offers "new and as-yet inconceivable carnal and affective relations between the sexes" (128) that unfold (in nonlinear fashion) from the present.
In chapter 8 Dolphijn and van der Tuin pursue new materialism's explicit address to the anthropocentrism contained in "human-subject-centered epistemology" (159). Along these lines they note a departure from the "prioritization of the subject" in new materialist thought, where subjectivity instead materializes as "a consequence rather than the fully-fledged starting point of an epistemic experience" (162). Although the authors point out that this thinking through subjectivity can respond to feminism's encounter with, and troubling of, the subject in its androcentric guises, the focus of the chapter lies with their elaboration of Michel Foucault's (affirmative) and Meillassoux's rewriting of the anthropocentric commitments within Kant's work and the Kantian philosophical tradition. In this undertaking we are presented with a highly accessible summary of Meillassoux's argument in After Finitude (see pages 168-72). From here, the authors move to the work of Brian Rotman and Vicki Kirby to find in their respective approaches to mathematics an argument for the "ontologically prior," wherein bodily force constitutes nature as mathematics, or mathematical practice, in nonlinear and nonanthropocentric terms.
Returning to the interviews that comprise the first part of New Materialisms, we see the monism or "philosophy of immanence" (85) that the authors establish as the hallmark of new materialism at work in each conversation (albeit differently engaged in Meillassoux's argument). The interviews offer clear introductions and explorations of these materialist philosophies/ontologies while laying out some of the political, ethical, and ecological commitments of new materialist thinking, as well as its address to humanist and modernist traditions. From Braidotti's and DeLanda's coining of a "neo-materialism" in their distinct approaches to matter as a "force of sexual differing" (Braidotti) (15) and "a historical process that is constitutive of the material world" (DeLanda) (15; original emphasis), to Barad's agential realism and Meillassoux's speculative materialism, we are provided with a snapshot of these scholars' thought that is helpfully presented in their own words.
A noticeable dimension of this series of interviews is the lack of straightforward consensus or uniformity across these scholars' work. Dolphijn and van der Tuin are not shy about these differences but actively identify them here and elsewhere in the text. Putting these dissonances to work allows the authors to differentiate the field, but it serves the stronger purpose of demonstrating the affirmative reading that they develop as a new materialist methodology and response to more traditional forms of critique. In this text, differences in ideas and conceptual trajectories are found in productive dialogue with one another, with some novel analyses emerging as a result. Although the interviews present a variance in perspectives on materiality, the coherence within these four theorists' positions is organized through the questions that Dolphijn and van der Tuin pose to each scholar, as well as in their discourse with these theorists' arguments in part II of the book, where they seek to demonstrate the "joint movements" (92) in their work.
This is a significant collection of interviews with contemporary material philosophers who, through their individual projects, widen the lens of what new materialism offers up as its terms and focus, while representing the diversity in thought that is coming to constitute something of a new materialist canon. The authors are to be commended for devising a very well informed set of interview questions that demonstrate a careful and rigorous reading of each theorist's work. Through their questions we gain a sense of what new materialism poses as its inquiry, and what its "interventions" might comprise philosophically, politically, and ethically.
For all of its attention to the temporal circulations and disarticulations that a new materialism offers, this book is, nonetheless, very much an anthology of its time. It takes us to a particular juncture in materialist thought that is represented through the interviews and the authors' considerations that follow. A number of voices operate in this text so that, to a degree, it provides a "survey" of its field that is carefully guided by its authors. Each of the interviews is helpfully related to the others in terms of its key claims, as well as threaded through Dolphijn and van der Tuin's own argument to underscore the strengths of a new materialist, cartographical methodology that they explore here. Accordingly, it is a welcome addition to the field of (feminist) new materialist scholarship and feminist philosophy.
 In a footnote to this comment, the authors declare their aim to demonstrate how new materialism "is immediately a feminism" (113).