RWDevCon Inspiration Talk – Identity by Alexis Gallagher

Clojure Defines An Identity As Having Many States

Rich Hickey is the creator of Clojure, which is a very cool Lisp dialect that runs on the JVM. As you can see, like Parfit, he has very dramatic hair. I guess you could say that Rich Hickey is an alpha nerd in the world of somewhat esoteric programming languages.

I was reminded of Rich Hickey and of Parfit’s discussion of identity when I heard Hickey talking about this:

This is Clojure’s model of time. It’s used to model change in the language. Hickey, I think he’s the only person that does this, defines identity as a noun to mean any continuously existing thing in the world, like a person, for example.

Every identity has a state that changes through time. A value, in the language, a value captures a snapshot of the state at some moment. The identity is that loop you can use to see the sequence of values that moves through time.

One of those values is a state. A value is just like the record captured by the scanner here on earth. It’s a snapshot of a moment.

People wonder what value types are for in Swift. Quick parentheses. You can think of value types as things that are really good for expressing values.

If you were going to use the Clojure model, use a reference type to describe an entity, like a person, but then that entity holds a value. It’s quality is right there at that moment in time, and that value can change, but that value, that snapshot, is always sort of mutable.

This is the parallel I noticed.

Numerically identical is to qualitatively identical just as same identity is to equal value.

So What Is Identity?

Later I learned that the Clojure model is actually echoing earlier work, I think.

This gentleman here is Eric Evans. He wrote a nice book called Domain-Driven Design around 2005.

He talks about the distinction between entities and value objects. It’s a very similar distinction. I think in retrospect, it’s not too surprising. You arrive at this kind of distinction between an entity and a value or a snapshot of it as soon as you try to specify exactly what is staying the same about something that might be completely changing.

What’s the answer? What is staying the same about something that might be completely changing? To be honest, I don’t know.

I think the Clojure model and Parfit’s model and what Evans have to say, I understand exactly what they are saying when they are talking about the snapshots, when they are talking about values or moments or qualities, but I feel like all of these models get slippery and tricky exactly when they try to nail down conceptually what identity is.

One of my takeaways is that identity is a fundamentally subtle and slightly problematic concept. When I was looking into this, I found the Stanford Encyclopedia of Philosophy has 10,000 words just defining “identity” in general, and then another 10,000 before it handles the special case of identity as it concerns people.

That’s why this parallel speaks to me because what it suggests is that the niggling puzzles that we encounter when we are trying to do data modeling in our applications are not trivialities. They are actually the protruding, tiny edge of much more profound, subtle issues under the surface that people can wrestle with and have thought about for a long time.

From My Own Experience

Let me offer my personal perspective on this also. This is a picture of San Francisco, specifically these are The Painted Ladies.

They are Victorian houses that people probably know from the opening of Full House.

This is near Alamo Park, which is not far from where I live. I grew up in San Francisco. Then I moved away, and after about 20 years, I moved back. That was about a year and a half ago.

When I moved back, for months, I had the eerie sort of spooky feeling that I was not in the real San Francisco anymore. In other words, it seemed like someone had created a perfect replica of San Francisco.

The old and new San Franciscos seemed to be equal, but not the same. It seemed like the new San Francisco was qualitatively identical. The streets hadn’t changed that much, but it wasn’t numerically identical, like the essence of San Francisco somehow was gone from it, like it was a perfect replica.

I think this is not an uncommon experience. We often have it connected to places that were really powerful early in our lives, like our home from childhood or a place where we had powerful friendships that really touched us.

I think it’s because of a feeling that was in us, at that age, and then when we get older, our feelings change and we come back and our feelings don’t match the place anymore. Then the place seems like its soul is missing.

It seems eerie, like you are meeting a familiar friend and they don’t recognize you anymore. When we visit the place again, our own emotions are different, and so there’s no fit. It’s nostalgic, and it can be unpleasant, like the place doesn’t recognize you.

My Childhood Identity

It’s not just about places. When I was walking around San Francisco having this feeling, I also had the feeling that I wasn’t myself anymore. I had the feeling that I wasn’t the real Alexis, almost as if I had been replicated.

Like it wasn’t me; like I was the ghost of myself. It kind of sucked. Why was I feeling that way?

Before I say that, let me show one more gentleman. Does anyone recognize this man?

Yeah, I see nods. This is Richard Feynman, the Nobel prize-winning physicist. He also wrote a very nice book of anecdotes which made him very popular. Lots of people read it.

Of course, he’s a canonical alpha nerd with dramatic hair. He won a Nobel prize. You can’t get more alpha nerd than that. Pretty good hair!

I think the reason I was having the feelings I was is because the last time I lived in San Francisco, I was graduating high school, and at that time, I was 100% obsessed with theoretical physics. Maybe I was 200% obsessed with theoretical physics.

In my mind, I thought Feynman was the coolest thing in the world. San Francisco, for me, for 20 years, had been captured in wax as a place that had these emotions of child Alexis, really interested in physics, wanting to be a physicist. Now I was coming back, and I was grown man Alexis with a family making software.

It was that mismatch that felt disturbing. It was that mismatch that made me feel like this wasn’t the real me. This wasn’t how things were imagined at some point.