*Sociobiological reductionism.* Wilson (1975), Buss (1989), and the evolutionary-psychology tradition read sexual behavior as the genome's strategy for replication, with affect as epiphenomenal scaffolding. The position rests on the explanatory power of selection: sexual behaviors that did not aid reproduction would not be reliably present in the biological record, and tracing observable patterns of attraction, mate choice, parental investment, and intersexual conflict back to selection pressures has yielded a substantial body of testable predictions that have repeatedly survived contact with the data. Any account of sexuality that ignored that substrate would be missing the structural floor on which the rest stands. The structural account preserves the evolutionary substrate — sexuality is the dominant recurrent solution, in eukaryotic lineages, to the variation requirement long-term continuation imposes ([§8.6.3](<8.6.3 What is Predicted.md>)) — and the explanatory power of selection within that frame. What the structural account adds is a distinction the reductive form collapses: between *reproductive function*, which the evolutionary substrate captures well, and *sexuality's broader embodied/intersubjective register*, which it does not. Sexuality is not exhausted by reproduction. Its operation as the densest register of intersubjective coupling — affect, attraction-as-registration-of-another-being, identity construction at self-aware depth, the production of new subjects as agentive choice rather than as biological default in beings capable of choosing — runs continuously alongside the reproductive function but is not reducible to it. Affect is real because registration is real; reducing affect to replication-strategy mistakes the substrate for the phenomenon, and treating same-sex coupling, post-reproductive sexuality, contraception-mediated reproduction, and sexual coupling as ends in themselves as anomalies-to-explain rather than as features the broader register makes immediately legible is one place where the reduction shows. The same substrate hosts both bacterial gradient-following and the deepest human intimacy; what differs is depth, not the kind of activity.

*Social constructionism.* Foucault (1976), Butler (1990), and the constructionist tradition read sexuality and gender as productions of historical discourse. The position rests on the variability of how sexuality is named, organized, regulated, and experienced across cultures and historical moments: what counts as sexual at all, who is permitted to do what with whom, which identity-positions are even available to the subjects who construct themselves around them, which forms of attention are sexually weighted versus unmarked, and how desire and constraint are jointly produced by power, language, and institution all vary in ways that resist substrate-only explanation. The constructionist's central observation — that identity is held in language, transmitted by institution, and shaped by power — is correct as far as it goes, and any account that treated identity-positions as substrates rather than as constructions would miss precisely what makes those positions historically and culturally located. The structural account preserves the constructed character of identity-positions — they are self-model constructions in the sense [§8.5](<8.5 Identity.md>) names, not substrates — without dissolving the substrate they are constructed against. The body is real, attraction is real, the affective architecture is shared across lineages and predates discourse, and the [§8.6.4](<8.6.4 What is Confirmed.md>) neural-correlate findings on orientation- and identity-architecture are not optional. What discourse constructs is how a particular being takes up its position in the field; the field itself is structural. The construction is real, person-specific, consequential, and dissolvable under the conditions [§8.5](<8.5 Identity.md>) names — but the substrate it constructs around is not negotiable in the same way.

*Sex-binary reductionism.* Contemporary sex-realist arguments — Stock (2021), Joyce (2021), Soh (2020), and the broader gender-critical literature — correctly insist that sexed embodiment is materially real, that reproductive biology is not a discursive artifact, and that institutional handling of identity categories has policy consequences that cannot be wished away. The structural account preserves all three claims. What it forecloses is the move from “one biological layer is real” to “that layer is the whole structure of sex and gender.” Five recurring inferential collapses drive the argument past what its substrate supports.

The gametic collapse moves from anisogamy — that sexually reproducing species use two gamete types — to the conclusion that sexed embodiment, development, attraction, and identity must therefore be binary in the same way; but anisogamy is one structural layer, not the whole architecture [§8.6.2](<8.6.2 What is Required.md>) documents. The chromosomal collapse moves from XX/XY's prevalence to the conclusion that sex is settled by chromosomes; but development is multilayered — genes, gonads, hormones, morphology, neural development, self-model — and atypical patterns at every layer are documented. The statistical collapse moves from population dimorphism to the conclusion that every token person is binary in the same way; but average differences between groups do not determine the architecture of the individual being. The policy collapse moves from “some institutions handle gender identity poorly” to “gender identity is therefore not real in the relevant sense”; but bad institutional handling does not falsify the phenomenon being handled. The construction collapse, running in the opposite direction, moves from “gender is socially constructed” to “gender is therefore arbitrary”; but self-models, languages, laws, and identities are constructed and causally real at once.

The structural account avoids all five by holding what each register tracks at its proper level: gametic polarity, chromosomal pattern, endocrine development, morphology, attraction, identity-position, and political standing are coupled registers, not interchangeable names for the same thing. Beneath the gametic and statistical collapses in particular lies a single distinction the reductions elide: at the substrate layer, sex-category membership tracks developmental organization toward a reproductive role, not the realized exercise of that function. The infertile, the post-reproductive, the prepubescent, and the celibate are not thereby removed from the category — which shows the category was never a per-token functional test but a claim about the developmental pathways a body's development instantiates, holding whether or not the function is ever exercised or succeeds.

Both collapses trade a type- or population-level fact for an individual functional criterion; the organization/function distinction forecloses that trade at its root. Two limits keep the distinction honest. First, the organization at issue is the typical bimodal pattern the chromosomal collapse already qualified, not a re-assertion of clean binary development: where organization is itself atypical — the documented intersex and disorders-of-sex-development conditions — category standing is genuinely intermediate rather than settled by a hidden exercised-function test, exactly as the multilayered account requires. Second, this is a claim about the substrate layer alone; it carries no verdict on social-category membership or on the self-model identity a person holds, which are the questions [§8.10](<8.10 Language.md>) and [§8.5](<8.5 Identity.md>) take up, and the organizational reading of sex-as-substrate licenses no inference to them. Adopting the developmental reading of sexed embodiment therefore concedes nothing to the move from substrate to identity that the gender-critical inference requires: the registers stay separate.

*Religious-metaphysical regulation.* Augustine, Aquinas, and the natural-law tradition, with cross-cultural variants in Confucian, Brahmanic, and Islamic ethics, did more than issue commands from outside Nature. They identified four real features of sexuality that thinner accounts tend to omit: that sexual coupling has in-built structural directionality and is not metaphysically inert; that the norms tracking it are not arbitrary divine fiat but constraints latent in what coupling is; that what is done sexually leaves enduring effects on the beings involved that mere consent or contract does not exhaust; and that sexuality participates in an order larger than the individual life, a kinship-and-generations order across which subjects are produced and sustained. Each of these phenomena is real, and a recreational-signaling or contractual-exchange account of sexuality cannot capture them. The structural account agrees with the tradition on the phenomena and corrects only the metaphysics. The directionality is what coupling is at the substrate level, with attraction-architecture, hormonal coordination, gestational physiology, and pair-bonding circuitry all converging on it; the norms tracking the directionality are [§8.12](<8.12 Morality.md>) structural-moral constraints on registration at maximum density, not divine fiat; the enduring effects are what registration in a recursive self-model does over time; the kinship-and-generations order is what intersubjective coupling at the density [§8.12](<8.12 Morality.md>) names already is, with no relocation above Nature required. The traditions accurately identified the weight, the directionality, the duration, and the order. They misidentified only the location of the source.

*Contemporary identity discourse.* Both poles of the public argument flatten one half of the substrate–self-model pair the framework holds together. The "gender is just biology" position collapses the [§8.5](<8.5 Identity.md>) self-model construction into the substrate, missing that the construction is real, person-specific, and consequential — that the self-model holds the position, and what the self-model holds is what it is to be that subject. The “gender is purely social construction” position collapses the substrate into discourse, missing that the body is real, attraction-architecture predates language and runs continuously across mammalian and avian lineages, and the [§8.6.4](<8.6.4 What is Confirmed.md>) neural-correlate findings are not optional. The framework holds both halves at once because both are present: [§8.5](<8.5 Identity.md>) self-models are constructed in a neural substrate that has structural properties, and neither half is the whole story. The reality and variability of sexual orientation and gender identity are grounded by the structural account directly: orientation- and identity-architecture have real substrate variability the empirical record confirms, and the self-model's construction of an identity-position around that architecture is real, constructed, consequential, and dissolvable under the conditions [§8.5](<8.5 Identity.md>) names for the self generally. The political weight derives from [§8.12](<8.12 Morality.md>): identity-positions are the beings subjects construct of themselves in the field of intersubjective coupling, and the structural account of moral standing applies to them as it applies to subjects in any other intersubjective register. Because standing is fixed at [§8.12](<8.12 Morality.md>) by the capacity for experience rather than by category-membership, the moral verdict is invariant across the constructionist and realist readings alike. Manne's (2017) distinction between sexism (the role-ascribing belief system) and misogyny (the enforcement mechanism that punishes deviation from the ascribed role) gives the [§8.12](<8.12 Morality.md>) framework analytic purchase here: misogyny is structural-moral violation directed at one being of the substrate-and-self-model pair, operating through the [§8.10](<8.10 Language.md>) language register to constrain the [§8.5](<8.5 Identity.md>) self-model. The structural account does not adjudicate the contested specifics of contemporary policy debate; it grounds the standing of the subjects whose positions are at stake and the empirical reality of the architectures their positions construct around.

> [!note]
> *Scope of the claim.* This account asserts two things and declines a third. It asserts that every subject at issue has moral standing fixed at [§8.12](<8.12 Morality.md>) by the capacity for experience, not by category-membership, so the moral verdict is invariant across the realist and constructionist readings alike. It asserts that the substrate architectures those identities construct around are empirically real and variable ([§8.6.4](<8.6.4 What is Confirmed.md>)). It declines to adjudicate the contested specifics of contemporary policy and etiquette debate. The account will be misread from both directions — as biological essentialism on one reading, as gender ideology on the other — and both misreadings collapse a register it holds apart: substrate ([§8.6.4](<8.6.4 What is Confirmed.md>)), self-model identity ([§8.5](<8.5 Identity.md>)), social category ([§8.10](<8.10 Language.md>)), and moral standing ([§8.12](<8.12 Morality.md>)) are coupled but distinct, and no claim at one level settles a question at another.

*Sexual violation.* The structural account names sexual coupling as [§8.12](<8.12 Morality.md>) morality at maximum density, where registration of one being by another is most direct. Sexual violation is the inversion at the same maximum: structural-moral failure at the register where the structural-moral demand is densest. The framework reads it not as an ordinary harm scaled up but as the violation specifically targeted at the position where the depth of registration is greatest. This is why the harm cannot be accounted for by injury-metrics alone — somatic recovery does not retire it — and why traumatic registration persists at depths the [§8.10](<8.10 Language.md>) language register cannot fully reach (Herman 1992; Walker 2013). Manne's (2017) reading of misogyny as enforcement-mechanism extends here: the prevalence of sexual violation as an instrument of role-enforcement, war, and political subordination is structural-moral failure operating systematically rather than incidentally. The framework does not explain why violation occurs — that is a question about substrate, history, institution, and agent — but it locates the wrong it represents at the precise point where intersubjective coupling is densest, and gives the [§8.12](<8.12 Morality.md>) framework analytic purchase on what the wrong consists in.

*The boundary between variation and violation.* Across the practices this section has not enumerated — commercial exchange, the range of kink and fetish, the configurations consenting adults arrive at in private — a single line does the work, and it is the same line drawn throughout: consent on the modal-depth standard ([§8.9.4](<8.9.4 What is Confirmed.md>)), the standing of every party ([§8.12](<8.12 Morality.md>)), and, where more than one bond is in play, non-corrosion ([§8.6](<8.6 Sexuality.md>)). What falls on the permitted side is variation, and variation is not the account's to moralize; what falls on the forbidden side is violation, and the account names it without hedging. The two verdicts are asymmetric by design. Where valid consent cannot be given — by a party who cannot map the possibility the act requires, whether through immaturity, incapacity, or coercion — or where a party lacks the standing the act presupposes, the coupling is ruled out, and no appeal to preference, custom, or privacy reopens the question. Where consent is real and standing is intact, the account issues no verdict beyond that one, and declines to convert its silence into either endorsement or prohibition. Commodification is the instructive case. The introduction of payment does not itself alter the consent analysis: an exchange of money between consenting adults whose consent meets the modal-depth standard is not structurally distinct, at the register this account speaks to, from the same act unpaid. What the word exploitation names is not the payment but the defeat of consent by the conditions around it — coercion, deception, or a desperation severe enough that the will behind the word lacked the mapped alternatives real consent requires; the wrong is a person used and mistreated, their consent hollowed out, not the presence of a price. The account locates the wrong there and leaves the policy question — how a shared structure should permit, regulate, or restrict such exchange — to Chapter 9, where institutional questions belong. One further distinction keeps the boundary honest: whether a practice is publicly acceptable is a question of the [§8.10](<8.10 Language.md>) social register, not of structural-moral standing, and the two must not be run together. That a practice offends public norm is not itself a structural wrong, and conducting it in private discharges the separate concern of not implicating non-consenting witnesses — but privacy addresses only that concern. It cannot launder a consent-or-standing violation into a permitted act: what is done to a non-consenting party, or to a party without standing, is no less a violation for being done unseen. The boundary is consent and standing, not visibility.

*Reproduction-choice.* Pregnancy gives the structural account its hardest application because one subject's body is the site where another possible subject is being produced. The [§8.7](<8.7 Mortality.md>) developmental-gradient result is therefore load-bearing here but not settled here: consciousness emerges as the neural architecture capable of integrated registration comes online, and standing comes into view by degrees rather than by binary switch. The [§8.7](<8.7 Mortality.md>) contribution is to name why reproduction-choice becomes agency at all. At the depth where a being can model its own future, its bodily conditions, its relations, and the possible production of another subject, reproduction is no longer only what coupling does. It becomes an object of self-modeling. The decision whether, when, and under what conditions to produce another subject belongs to the agency of the already-existing subject whose body bears the process. The developing being's emerging standing matters once the [§8.7](<8.7 Mortality.md>) developmental threshold begins to be reached; the pregnant subject's standing is already present throughout. Chapter 9 carries the political application because the question then becomes institutional: how should a shared structure protect an existing subject's bodily autonomy while registering the developing standing of another being as it comes into being?

Sexuality read structurally as the densest register of intersubjective coupling preserves what each rival tradition was tracking while refusing each collapse it forced. Sociobiology's reproductive substrate is real and is one layer rather than the whole; constructionism's identity-construction is real and is built against a substrate that does not negotiate at the same rate; sex-binary reductionism's biological reality is real and does not license the five collapses (gametic, chromosomal, statistical, policy, construction) that drive its inference past where the substrate goes; religious-metaphysical regulation's directionality, duration, and order are real and their source is the medium rather than the agent it was personified into; contemporary identity discourse's substrate-and-self-model pair holds at both halves rather than at either alone. Sexual violation is [§8.12](<8.12 Morality.md>) morality at maximum density inverted; reproduction-choice is where the developmental-gradient result meets the pregnant subject's already-present standing. The structural counterpart is taken up at [§8.7](<8.7 Mortality.md>) — drive's aversion-pole at its limit.


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← [8.6.4 What is Confirmed](<8.6.4 What is Confirmed.md>) | [8.7 Mortality](<8.7 Mortality.md>) →
