I am not a millennial. Or am I? It’s a trick question. I’m a “cusper,” born near the divide. Specifically, I am one of the “Xennials,” the microgeneration of people born between 1977 and 1983. We cannot be tidily bundled in with the optimistic millennials, speciously characterised by their narcissism and political correctness, nor are we quite at home among disaffected but cool Generation X. We remember analogue childhoods, but came into fully digital adulthoods, and that combination of experiences tends to set us apart.

Living in the penumbra can be culturally isolating, but it also offers opportunities to serve as a bridge between today’s young and old. Researchers have suggested that “members of microgenerations … may be a key to reducing workplace friction between employees of different generations”. As a philosopher, I focus on the philosophy of romantic relationships, where all kinds of hot topics are bubbling up right now along intergenerational fault lines. These tend to cluster around attitudes to monogamy and commitment, as well as the dearth or excess (depending on whom you ask) of casual sex that young people have these days.

Dubbed the “gender-fluid generation”, millennials have been blamed (or credited) with dismantling what was once a robust, scientifically established binary distinction, turning it into some sort of hazy social construct, a spectrum, or nothing at all. But to study romance is to study gender – the two are bound up together. Drawing on ideas from the French philosopher Simone de Beauvoir, we can see that gender and romance are socially constructed in terms of each other. It is literally of the essence of both romance and femininity that our romantic fairy tale has two main characters – the Cinderella and Prince Charming archetypes – whose respective genders are crucial for understanding how romantic ideals impact our lives.

So it’s no coincidence that society perennially targets relationships and gender as the key areas where young people are “doing it wrong”. The ongoing loosening of gender roles is of a piece with the blurring of our social perception of what a romantic relationship looks like. To take an easy contemporary example: if we decide that being “in love” doesn’t require one woman and one man, the gender roles standardly assigned within the heteronormative couple (homemaker and provider) are simultaneously called into question.

So far, so good. The complaint is that it’s all gone too far: millennials are not liberating, but killing off both gender and relationships. What happened to good old dating – having an actual boyfriend or girlfriend, instead of leaving everything so vague, so casual, or so … non-existent? For that matter, what’s wrong with just being a boy or a girl? Why does gender itself have to be “fluid” or “whatever” now?

In my own experience teaching young students, I’ve found them for the most part knowledgeable, thoughtful, careful, and interesting. They aren’t, of course, all of one opinion; rather, they start from a cultural baseline that has equipped them to understand certain subtleties of ideology and to manipulate sophisticated concepts. In a way, their facility in this intellectual space is no different from their facility with technology: concepts are, after all, technologies of the mind. As a Xennial, I acquired these facilities at a much later stage of my life, and most of my students navigate easily around arguments about gender and romance that are quite challenging for many of the established professors I know.

Perhaps I’m biased, being a cusper, but I believe there are some philosophical tools that can help us bridge the gap between young and old. One device that can illuminate some of the dynamics around gender and romance is an understanding of vagueness. In particular, it’s crucial to appreciate that in calling something vague, we are not saying that it doesn’t matter, that it isn’t real, or that anything goes.

Consider mountains. They are among philosophers’ favourite examples of vague entities: where exactly does Mount Everest begin or end, after all? But we don’t generally think this means that mountains aren’t real, or don’t matter. Likewise, the vagueness of generations is responsible for my “Xennial” status, but that doesn’t mean there’s no such thing as a generation, or that everybody is an Xennial now, or anything like that. Vagueness is just a fact of life, along with other facts.

In much the same way, calling gender vague (or fluid or flexible or multi-dimensional or whatever) does not imply that it is non-existent or insignificant, that anything goes, or that there are no real boys or real girls any more. It is, rather, a way of appreciating that human life is complicated.

There is a temptation to push back: gender – or at least sex – must be determinate, because it’s about biology, which is a science, and science is not vague. But a little philosophy of science also hands us the tools to chip away at such simplistic thinking.

The English mathematician and philosopher Alfred North Whitehead famously cautioned that “the final outlook of Philosophic thought cannot be based upon the exact statements which form the basis of special sciences” because, as he succinctly put it, “the exactness is a fake.” Contemporary metaphysician Elizabeth Barnes argues that even fundamental physics – that most scientific of sciences – is shot through with vagueness. She offers as an example the process through which Einsteinium is created:

Atomic bonds don’t form instantaneously; electrons, protons, and neutrons don’t just automatically switch from being independent to being part of an atom. It takes several nanoseconds for the bonds to form, and so it seems that at some point along this process it will be indeterminate whether the particles in question instantiate the property of being Einsteinium.

It hardly needs saying that human biology is a lot messier than fundamental physics. The latter is moreover mutable: we are constantly intervening on our own biology, be it by taking medication, doing weight training, undergoing laser eye surgery, or just eating a banana. Our growing understanding of the world’s – and our own – vagueness, complexity, and dynamism is an inter-disciplinary success story. It tracks intellectual progress.

The second-wave feminists I learned from in the 1980s were working to drag the (mis)conception of gender as a rigid biological binary into the light, where it began disintegrating. In so doing, however, they raised the stakes: once we know we’re dealing with a social construct, we see how important our attitudes and practices really are. Such things determine what gender is, who is and who is not a woman, and so on.

The social construction of gender might help explain (without excusing) the vitriol with which questions about gender are now debated and policed in some quarters. It may feel desperately important to reinforce the old idea that there are, as a matter of unalterable biological fact, exactly two human sexes (no vagueness, no complexity, no dynamism): after all, once we stop reinforcing it, it will no longer be true. As de Beauvoir put it: “one is not born, but rather becomes, a woman”.

This means the “natal woman” is a creature of ideologically motivated pseudo-science, rather than unalterable biological fact. The reanimated corpse of biological determinism is now trampling into far too many contemporary discussions of trans rights, and should be laid back to rest. Maybe millennials are deadly, but there are some things that should be killed off.

Ultimately, the millennial conception of gender and romantic fluidity is the true descendant of the challenge that second-wave feminists posed to fixed gender roles. It is disappointing that anything resembling the old conception of static binary sex is still with us at all, given how long it has spent under explicit and widespread scrutiny as a damaging and contingent construct.

Still, in the end the younger generation wins every debate, because that’s how the wheel rolls. I for one welcome our new millennial overlords and overladies and whatever.

Carrie Jenkins is Professor of Philosophy at the University of British Columbia. She is the author of What Love Is and What It Could Be. She also runs the Labels of Love podcast.

This article is part of the Agora series, a collaboration between the New Statesman and Aaron James Wendland, Professor of Philosophy at the Higher School of Economics. He tweets @ajwendland.