Over the last several years, “mirror neurons” have become key players in biological research and popular discourse. They are alleged to endow our brains with a built-in capacity for empathy, mediating sociality and binding us to the suffering of others. According to the critic Victoria Pitts-Taylor, mirror neurons enable the brain to “[generate] a grasp of the other, not with language and thinking but via simulated action and feeling.” This sounds grand. But, among other problems, it makes mirroring processes seem, in Pitts-Taylor’s words, “generic, universal, and highly normative rather than ontogenetically specific and multiple.” What does this mean — and why should we care? Pitts-Taylor, who calls herself a “new feminist materialist,” takes up the (alas, still timely) case of Amadou Diallo, the 23-year-old African immigrant who, in 1999, was shot and killed by four members of the New York City Police Department. They fired 41 shots, 19 of which struck Diallo, because they mistakenly believed that he was drawing a gun. We could read this 1999 scenario, as well as its many recent analogues, as simply a tragic instance of the failure of simulated action — mirror neurons not doing their job — resulting in a lamentable misunderstanding of intent. Pitts-Taylor’s point is more complicated. It takes issue with the false universalism implied by phrases like “the brain” and “the body.”
The problem, in other words, is that neurobiologists conceive of mirroring in generic terms and fail to grapple with the specificities of the social divisions that, in the Diallo case and others like it, made miscomprehension so much more likely. Being in a body, or “embodiment” as it’s called, isn’t just “a common thread that unites us.” In fact, embodiment is affected by the usual suspects: “race, class, gender, and other patterns of social difference.” And this means that it’s “enmeshed in suffering” and “violence.” In a nutshell, “embodiment is not exactly the same for everyone, and simulation cannot guarantee sociality or empathy.” If true understanding is possible across social chasms, it will take much more than mirror neurons, or stories about neurons, to achieve it.
The emergence of mirror neurons as subjects of research represents an opportunity to imagine how brains and minds are at once biological and social. Along with the rest of us, neuroscientists need to scrutinize the social part of a biosocial hybrid. As Pitts-Taylor puts it, “perception takes place in worldly contexts that render automatic simulation a poor model for intersubjective understanding.” In other words, a narrow account of the biology of empathy is dangerous when worldly contexts — and “social” backstories — are elided. In her new book, The Brain’s Body, Pitts-Taylor, who is a professor of feminist, gender, and sexuality studies at Wesleyan University, does not explicitly discuss the more recent instances of police shootings of unarmed African Americans, nor their social contexts, but they hover in the margins of her text, and certainly in readers’ minds; such cases clearly demonstrate the limits of this line of neuroscientific research. The notion of humans-as-“mirrorers” simply fails to account for the consistent reproduction of social injustice and state-sanctioned violence.
A phrase like “Black Lives Matter” resonates with new feminist materialism because mattering is precisely the point. Like The Brain’s Body, Pitts-Taylor’s edited volume of essays entitled Mattering addresses a host of topics that crisscross the worlds of politics and science, invoking the limits of mirroring and the dynamics of “mattering.”
The topics that are deemed to “matter” in these two books include: Border control through biometric technologies; brain-computer interfaces; the economics of egg donation; psychotropic drugs in prisons; randomized clinical trials; Colony Collapse Disorder; toxic bodies; ADHD; empathy; and kinship. Both volumes ask us to consider how such things matter, in all senses of the word: How do they acquire social, political, and ethical significance? How do they emerge as material stuff we can talk about? How might our theories of power, differences, and social inequalities be informed by theories about how the things of the world acquire form and substance? For the crop of scholars who call themselves new feminist materialists, such questions open up a new direction in feminist theory — and avenues for closely and coherently engaging with cutting-edge developments in science and technology, of which mirror neurons are just one example. It also enables them systematically to repudiate philosophical dualisms, rejecting outright some of the problematic mainstays of 20th-century social thought.
To start with the last point first: new feminist materialism (or new materialist feminism — Pitts-Taylor’s contributors use both nomenclatures, so take your pick) targets the “linguistic turn” in social theory. This is the general view, expressed in various theoretical approaches such as social constructionism and poststructuralism, that the world takes shape for us through the social lenses we inherit and through our processes of describing it. For example, social constructionist feminists of the 1970s developed a critique of the idea that gender differences in society are a biological given — not to be questioned — by drawing a sharp divide between “sex” and “gender”: biological sex was the bare-bones and relatively trivial biological substrate, on top of which societies constructed potent but arbitrary pink-and-blue distinctions that we now recognize as the gender order.  The poststructuralist feminists of the 1990s declined to cede even that much ground to biology. They adopted gender theorist Judith Butler’s argument that sexed bodies are themselves produced through the repeated cultural performances of gender.  Bodies became “texts,” which meant that cultural critics could “decipher” them. For all their differences, these approaches both privileged representations of the stuff of the world, and their political agendas focused on replacing repressive representations with alternative ones. In this regard, both approaches preserved and strengthened the hoary dualisms of Western thought — reality/representation, nature/culture, biology/society, body/mind, matter/spirit, deed/word — in each case treating the latter term as the key to understanding the former.
In response, new materialism reconceptualizes “the terms of social theory, such that the social is seen as a part of, rather than distinct from, the natural, an undertaking that requires a rethinking of the natural too.” In this newly monist view, the proper response to the threat of biological determinism — the claim that biology is destiny or that our fate lies in our genes — is not to reject the natural sciences and assert the primacy of the social, nor indeed to treat the world as text, but rather to grasp the inseparability of the “bio” and the “social,” as captured in the word “biosocial.” In place of a linguistic process of representing the world, the new materialism proposes “mattering” as the generative process through which matter comes into being. Material stuff — bodies, tools, objects — are understood as imbued with vitality and dynamic force. This is a philosophical claim, but one that entails a political sensibility. And while materialism is a venerable school of thought, this conception of “mattering” seems, as I have suggested, very much of the moment.
The new feminist materialism has many sources of inspiration, and not all of its adherents agree on all points (or even, necessarily, adopt the moniker), but one of the most consistent reference points is the work of the philosopher Karen Barad, a theoretical physicist by training who is now a professor of feminist studies, philosophy, and history of consciousness at the University of California, Santa Cruz. Drawing on insights from quantum theory and science studies, she develops an approach she calls “agential realism.” Criticizing Butler’s failure to “give us any insights into how to take account of the material constraints, the material dimensions of agency, and the material dimensions of regulatory practices,”  Barad seeks to transcend the notion of a clear divide between the realms of the material and the discursive. Invoking Heisenberg’s famous uncertainty principle, she challenges the idea of a strict separation in scientific description — or indeed in any description of the world — between the apparatus that generates measurements, the object being measured, and the researchers doing the measuring. All of these are necessarily entangled and shape one another. Therefore, Barad’s conception of how reality is materialized and rendered perceptible repudiates any simple understanding of science as a practice that uses the representational capacities of human discourse to depict, objectively, an independent reality.
III. Is feminist materialism a new development?
Any school of thought that dares call itself “new” inevitably subjects itself to debates about whether there’s anything new under the sun. The new feminist materialism is no exception. Many of the points made by adherents would be uncontroversial to academics in the field of science and technology studies, and particular stances are well anticipated by the work of feminist science studies scholars like Anne Fausto-Sterling.  Several of the essays in Mattering rightly point to multiple precursors — for example, the highly original work of Donna Haraway, which, since the 1980s, has challenged the divides between nature and culture, the material and the semiotic, humans and animals, and humans and machines.  And some scholars have wondered about new feminist materialism’s relationship to other, “older” materialisms — for example, the historical materialism of Karl Marx. (Two of the essays in Mattering tackle this question.) To my mind, what gives the new materialism its most legitimate claim to newness is its sustained engagement with cutting-edge developments in the sciences.
Where Barad looked to physics, Pitts-Taylor and her colleagues look to biology. They are fascinated not only by concepts like mirroring, but also by recent theories of epigenetics and neural plasticity. In place of the old genetics, which severed “genes” from “environments” and then asked how they interact, epigenetics is a theory of entanglement: it presents organismic development in terms of dynamics, examining how exposures and experiences modulate the very expression of genes.  Theories of neural plasticity — which treat the brain not as “hardwired” but as malleable and self-organizing in response to life experiences — are similarly concordant with the tenets of the new materialism. Yet, very much to their credit, the new feminist materialists are not just opportunistic adopters of trendy science. As these two volumes make clear, their agenda is to use the tools of feminism and science studies in a critical manner to examine both the promise and the pitfalls lurking on the scientific frontier.
Pitts-Taylor does this well in The Brain’s Body and less well in Mattering. The first is an engrossing book that is slim but not slight, neatly tying up the threads I have highlighted here. It deploys diverse theoretical resources — including feminist science studies, queer theory, and disability studies — to “address, on the one hand, how social norms, power and inequality affect representations of the brain and, on the other, how they are understood to literally entangle with neurobiological processes.”
For example, rather than embrace research on brain plasticity as telling an agreeable tale of human freedom, flexibility, and adaptability, Pitts-Taylor considers findings that clearly matter — the effects of childhood poverty on the neurological development of language systems — and shows just how entangled this research is with imaginings of social “others.” Calling attention to researchers’ shallow conceptualization of social processes, she points out that aspects of class and race differences are experienced in specific, embodied ways, which affect how brains develop. As she notes, “when a childhood is marked by economic vulnerability, chronic stress, and food insecurity, the question is not whether this is experienced neurobiologically.” Instead, we should ask how this process plays out for each marginalized group, what social mechanisms and neural pathways lie between “exposure” and “outcome,” and how we can be sure that we’re accurately measuring what we think we’re observing. It should be evident that interventions of this sort are by no means “anti-science” but rather reflect the strongest commitment to promoting the best science possible.
I wish I could praise Pitts-Taylor’s edited volume Mattering with the same degree of enthusiasm. Its 16 essays explore theoretical debates about the new feminist materialism, apply the approach to various scientific fields, use it to shed light on contemporary political debates, and reflect on methodological questions. Many of the individual essays are interesting, and they certainly reinforce — through repetition across pieces, which, given the complexity of the ideas, is not unhelpful — the key themes, tenets, and touchstones of new feminist materialism. And yet, like many edited volumes, the book doesn’t quite develop a narrative arc or gel into a fully coherent whole. Possibly because of their origins as papers at a conference, quite a few of the essays feel like a conversation among insiders rather than an invitation to the rest of us.
Perhaps most disappointing, therefore, is the section that explicitly seeks to flesh out the broader political implications of new feminist materialist analyses. Of those essays, Teena Gabrielson’s stands out for its virtues, nicely capturing moments in the history of toxicology to demonstrate how the invention of the interpretive technique of the dose-response curve materialized a “toxic body,” which may often occlude from view the human perpetrators of environmental harms: “in contrast to the nineteenth-century poisoned corpse, the toxic body was cast as a mere by-product of industrial processes.” But other essays turn to familiar topics — such as the administration of medications to children to treat attention deficit hyperactivity disorder — and dress up well-known critiques in the language of new materialism. A promising analysis by Josef Barla examines a UK pilot project to use DNA ancestry testing and isotope analysis to police the border and screen refugees by identifying their “true” countries of origin — but it seemed to me to go off the rhetorical deep end by claiming that the case “demonstrates that the border neither begins nor ends at the geographical or political borders of the EU, but is relocated into the depths of the body.” The more I thought about that claim, the less I knew what it meant. Yes, through biometric technologies state surveillance is interiorized. But in what sense are borders brought inside the body? That language calls to mind dividing lines running within us, such that some parts of us are “inside” the country while other parts are kept “outside.” And that isn’t what the technology does.
In short, readers will find much to think about in Mattering, but those who want a concise demonstration of what the perspective can accomplish would be better served by turning to The Brain’s Body and spending some time with its careful, if complicated, arguments. More generally, the new feminist materialism, in its persistent concern with things that matter, resonates with a larger corpus of work in science studies that attends to what the sociologist of science Bruno Latour has called “matters of concern” — including matters that reveal the tight intertwining of the political and the technoscientific.  As sociologist Ruha Benjamin argues in a recent essay, such work may transform our understanding of racism by finding it not just “on the bloody floors of Charleston churches and the dashboard cameras on Texas highways,” but also “in the smart sounding logics of textbooks, policy statements, court rulings, science journals, and cutting edge technologies.”  This broader body of work also goes beyond the concerns of these two volumes to consider how the very domain of politics — and our ideas of what it means to be a citizen or an activist — is reconfigured by new developments in the worlds of science and technology.
Steven Epstein, professor of sociology and John C. Shaffer Professor in the Humanities at Northwestern University, is the author of Impure Science: AIDS, Activism, and the Politics of Knowledge and Inclusion: The Politics of Difference in Medical Research.
 See, for example, Gayle Rubin, “The Traffic in Women: Notes on the ‘Political Economy’ of Sex,” 157-210 in Toward an Anthropology of Women, ed. Rayna Rapp Reiter (New York: Monthly Review Press, 1975).
 Judith Butler, Bodies That Matter: On the Discursive Limits of “Sex.” New York: Routledge, 1993.
 Karen Barad, “Getting Real: Technoscientific Practices and the Materialization of Reality,” differences: A Journal of Feminist Cultural Studies 10, no. 2 (Summer 1998): 93. See also Karen Barad, Meeting the Universe Halfway: Quantum Physics and the Entanglement of Matter and Meaning (Durham, NC: Duke University Press, 2007).
 Anne Fausto-Sterling, Sexing the Body: Gender Politics and the Construction of Sexuality (New York: Basic Books, 2000); Anne Fausto-Sterling, “The Bare Bones of Sex: Part 1 – Sex and Gender,” Signs 30, no. 2 (2005): 1491-527.
 Donna J. Haraway, “A Manifesto for Cyborgs: Science, Technology, and Socialist Feminism in the 1980s,” Socialist Review 15, no. 2 (1985): 65-107. Another important precursor is Elizabeth A. Wilson, Psychosomatic: Feminism and the Neurological Body (Durham, NC: Duke University Press, 2004).
 As Lisa H. Weasel explains in her essay in Mattering: “epigenetics focuses instead on the ways in which environmental exposures and experiences, including dietary intake, chemical contamination, and psychosocial stressors, interact within a physiological milieu to toggle tiny methyl and acetyl groups tagging DNA nucleotides and the proteins that wrap and unwind DNA, opening it to expression or closing off its potential transcription or translation.”
 Bruno Latour, “Why Has Critique Run out of Steam? From Matters of Fact to Matters of Concern,” Critical Inquiry 30, no. 2 (Winter 2004): 225-48.
 Ruha Benjamin, “Catching Our Breath: Critical Race STS and the Carceral Imagination,” Engaging Science, Technology, and Society 2 (2016): 148-49. See also Alondra Nelson, The Social Life of DNA: Race, Reparations, and Reconciliation after the Genome (New York: Beacon Press, 2016).