My sister, who is a Ph.D. sociologist, first introduced me to the sociological concept of intersectionality. Like many academic sociological terms, it is often misunderstood and misrepresented in popular discourse. But I found a simple way to approach it by thinking about it with my math brain¹. I think I can explain it in way that is easy to understand, however you might feel about math.

What is intersectionality about?

Intersectionality originally arose from the research of Black women², such as Kimberlé Crenshaw, who noted that Black studies and women’s studies were insufficient to describe the Black women’s experience. There are critical issues particular to the intersection of Black identity and womanhood.

An example of such an issue would be the topic of hair care for for Black women, a subject my sister researched for her PhD and wrote a book on. Institutional rules around hair, such as prohibition of afro hair styles, put a particular burden on Black women that is distinct from men (who can often easily opt for short hair) and non-Black women (who disproportionately have hair whose natural state is considered acceptable). Some of the implications:

• Black women spend more time and money on hair care
• Black women are exposed to dangerous chemicals used for hair straightening, especially hairdressers
• Black women may avoid exercising or swimming to preserve their hair style, impacting their wellness

Altogether, this is a meaningful impact impact on their lives.

And so far, we’re only talking about two identities; people are far more complex than that. Class, religion, sexual orientation, language, national heritage, regional origin, etc. create a rich tapestry of identity. Furthermore, most of these identities are complex and context-dependent.

A little math

When I encountered intersectionality in my sister’s work, I was in grad school, studying signal processing applied to audio signals. It immediately occurred to me that intersectionality is the insight that identity is nonlinear³. In signal processing, a linear system is one that can always be viewed by how it acts on each aspect of its input. It follows this rule:

Thinking about the hair example, if f represents the burden of rules on hair, x is Black identity, and y is womanhood identity. In a simple society, you could look at the effects of f on each identity separately and then combined your insights to know how combinations of identities are experienced. As mentioned above, this doesn’t hold.

This implies that it is valuable to do qualitative research, to look for insights that don’t fall out of large studies designed to isolate single variables, which depend on the assumption of linearity. On one hand, this is sad, because it means there’s so much we can never know about society, because it’s impractical to study every possible intersectional identity. But I also find this exciting, because it also implies that individual lived experiences will forever be unique and valuable. There’s more to each of us than what research can explain.

1. This insight in this piece happened years ago, but this post was inspired by a good friend of mine sharing an article, The Linear Fallacy, to our group chat of scientists and technologists. The article critiques over-reliance on the assumption of linearity, especially outside of rigorous mathematical models. ↩︎
2. Critical race theory, to be specific. ↩︎
3. Let me caveat this by saying that social science is not math. Dr. Crenshaw may not have had nonlinearity in mind when she developed the concept, so it’s worth studying what actual sociologists say. But the analogy has been useful for me, as someone who comes from a tech background, rather than liberal arts. ↩︎