Segmentarity is when we divide things up, into segments. There are countless ways you can divide things. It depends what you’re trying to do.
Segmentarity works “in a circular fashion,” in ever wider circles, or “in a linear fashion.” When circular the segments proceed outward, like me, my street, my town, my country, the world, the galaxy … So when I’m right at the centre I belong to the outer circles too. Linear segmentarity, on the other hand, means you “proceed” from one point to the next, moving on to one segment and leaving another behind. I leave my street, and go to another street to enter my workplace. Circularly, I’m still in my town, my country … But linearly I’ve moved because I’ve moved to another street.
Linear segmentarity means you’re here, and not there. Anything can be divided into segments, you just need to want to do it. So society is divided up: home, work, school, and so on, describe different places for activity. When you’re in school, you’re not at home, and so different rules apply. “You’re not at home anymore,” Deleuze and Guattari write: this is what they tell you when you’re at school, or when you’re in the army. You’re here, and not there, and so different rules apply.
“Man” and “woman” describe segments too. “Be a man!” is intended to remind you what side you belong to, what segment you stand upon. Again, so that you know what rules you’re supposed to be following. If you feel that people need rules to follow, dividing things up is a method for justifying these rules. Divide and conquer.
In our society, we do this to ourselves, we know how the segments are divided. And many of us know that these divisions are man-made, but we treat them often as if they were the work of Nature, and unalterable. Because if it turned out we were making all this up ourselves, and that we were capable of making new division and new rules, what sense would there be in following the rules we have?