There are 10 kinds of people.

This story isn't about software, either. The title is the only computer science reference in the whole thing. It reaches no conclusion. It likely does not even make any points that you haven't thought of yourself at some point, though if I'm lucky it hasn't been presented to you before in quite this way. It might even be offensive.

Consider two groups of people. The demographics between these groups are similar in every externally observable way: all ranges of age, all genders, all manners of ethnicity[1], some with good fashion sense and some without, some tall and some short, some bald and some quite hairy. If a member of one of these groups stood in front of you, you would not be able to classify them into either group even after detailed study, but after five minutes of casual conversation it should become clear to which group they belong.

I'm going to call these groups A and B. I don't know what to call them; or at least, I don't know what labels I could give them that would not cause preconceptions that would detract from the point I'm trying to make. So, for now, they are A and B.

Over the past week, I've had the pleasure of sharing several meals on board a train with randomly assigned strangers seated at the table, different people each time. After some of these meals I was very concerned over how I was taking part in the conversation at the table. After some others, I was very pleased and came out feeling that we had all had a good time. And then there was one meal where I was convinced that half the table consisted of rude morons, and that the one other diner and I were barely putting up with it. What could have caused such enormous differences in experience?

Topics during all of these conversations were fairly similar, very casual, and even when some of the diners shared a common professional background they did not delve into it too deeply. Discussions centred around where past travels had taken them, what they were going to do at their destination, amusing things that they had experienced, and other such mundane things.

During the bad conversations, I found myself trying to get words in edgewise because there was a constant stream of words coming from somewhere, followed by awkward pauses. I observed that, any time I said anything during one of these awkward pauses, either someone interrupted to say something completely unrelated, or an even longer awkward pause followed. The only reason I spoke up at all was because it felt supremely rude not to. I had no idea what words were about to come out of my mouth at any given time, but they were always the wrong ones. Discussions tended to go back and forth very quickly, with one person saying something, another person jumping in to say something that sounded knowledgeable on some aspect of that topic, then another, then another. The facts being thrown into the conversation tended to be unverifiable and isolated, memorized: that some city had the largest whatever, I heard that some other city had the first whatever, I heard that a third city had just finished building a whatever. After each of these facts was thrown out, there was much nodding and agreeing, and meanwhile something else that was vaguely related was thrown out. And then a pause, at which time I said something inappropriate and crass, and then another pause. I imagine that everyone at the table thought I was a moron. They would have been right, based on what they would have observed. Let's call the people who took part in this style of conversation group A. Dealings with group A make me feel threatened and stupid.

During good conversations, there was no hurry to say anything because there were always pleasant pauses in between exchanges. There was no interrupting, topics took several minutes to come to a natural completion before a new topic was introduced, often one related to something mentioned during an earlier topic. Pauses did not feel awkward but rather were invitations for something new to discuss as they indicated that everyone had said their peace. There was no reason to revisit topics because everything to say about each concluded topic had already been said. I had no trouble making my points because I could plan out what I was going to say before saying it, instead of feeling pressured into automatically blurting out just anything. These were extremely pleasant conversations that could have continued for hours had we not had to make room for the next seating. I felt I had made a good impression on the others and they had made good impressions on me. Let's call the people who took part in this style of conversation group B. Dealings with group B make me feel clever, appreciated, calm, and content. In one case I even felt inspired to make an amusing remark as I excused myself from the table, a rarity for me.

During the in-between conversation, I was seated facing one diner who was getting more and more impatient as time went on, with two other cheerful and animated diners seated next to us and facing each other. All four at the table were seated independently and did not know one another. The latter two talked and talked. Whenever the one diner or I said anything, one or both of the two immediately jumped in and made a barely related observation, and then they continued talking to each other. I found the one diner to be saying interesting things and made an effort to reply, but there was a stream of banality coming from my right that made it difficult to do. I will make a leap of faith here and, without evidence or reasoning, say that the two diners belong to group A and the one diner to group B.

Is this just natural variation in personality and style?

Remembering back to the things that were said, diners that I labelled group A had occupations including oil rig operator, retired homemaker, truck driver, and television video editor. Diners that I labelled group B had occupations including retired railroad engineer, IT project manager, fitness instructor (married to the IT project manager), and software developer.

Does it still seem like just natural variation in personality and style?

Group A is what you might call normal people. They have positive interactions with other group A people in the same way that Sims do. You could almost see the speech bubbles popping up: Soccer ball? Yes, soccer ball! Nodding, smiling, +1 to relationship. No content need ever be exchanged, and the goal is to find as many things to agree on as possible. They have negative interactions with group B people: soccer balls and dollar signs and houses and dogs pop up all over the screen, obscuring the paragraph response coming back from the other side.

Group B is what I will just call nerds. (Now that I think of it this way, I'm surprised that I've met on board just as many in this group as in the other. Would I be crass if I suggested that proportionally more group B people can afford to take the train?) They have positive interactions with other group B people by finding as many things to disagree on as possible, explaining why a different view is held without ever trying to convince anyone to change their own, and falling back to different ways of thinking about the viewpoint if there happens to be agreement. They have negative interactions with group A people because group A people produce so many words without actually ever saying anything, and it's exhausting.

Is one group superior to the other? I can't imagine many of one group being happy in the other group's occupations, and I can't imagine many of one group could even do the other group's occupations. In some ways, then, yes. In other ways, since we need both, no; they're just different.

I've said many words here without saying anything. What group am I in?

[1] Actually, not really. Every single fellow diner, and for that matter every single person I've seen on board who wasn't wearing a staff uniform, was Caucasian. I don't think it changes this story substantially, though. I would be interested to find out why the vast majority of train riders share a common ethnicity.