Two Questions, Out Loud

The first time Jim Rutt mentioned the two questions, I was barely paying attention — but both stuck, and they stuck together. He was interviewing someone — I don’t remember who, I don’t remember the episode — and the topic drifted, as topics on his show drift, into what I would later recognize as the fixed gesture: he announced them paired, in the ranking cadence, the biggest question in science is why something and not nothing; the second-biggest is the Fermi paradox. The guest nodded politely, they moved on, and I didn’t notice I had filed both away until they came back, two weeks later, in another episode with another guest. For reasons I’ll try to reconstruct further down, the two questions, in some particular way, always stuck with me — the fact that I was listening to the Jim Rutt Show while doing the dishes, and not, say, to something with more human company involved, was already circumstantial evidence that my head had been built to stick to them. Hearing Rutt announce the pair was, then, like hearing someone reach for two old standards at the piano in quick succession. Pleasant, recognizable, no information — but recognized whole, and recognized as a pair.

The repetition is what made the package visible. The second time I noticed the pair — noticed I was noticing. A few weeks later, a third time, and this time the guest wasn’t on metaphysics or SETI or anything that would invite the pair; they were talking about something else entirely, and the pair came through whole anyway, tucked into some aside, with the same framing sentence. By the fifth time — I am not sure it was the fifth, but it was that order of magnitude — I had stopped finding it pleasant-and-recognizable and was starting to find it strange. The strange thing wasn’t Rutt coming back to Fermi. The strange thing was him coming back to the pair, in order, with the framing intact, even when nobody had opened the door to either one.

Most intellectuals don’t do this. Most intellectuals are moved by the next shiny thing. You watch them across years and they’re always orbiting whatever conceptual fashion is in the air — complexity, AI, prediction markets, longevity, post-rationalism, fill in the blank. Their pivot questions change with the season. Last year I was thinking about X, this year I’m thinking about Y — that’s the structure, and it’s the structure for almost everyone, including me. Rutt has had two questions for over a decade. He brings them up on roughly half his episodes. He admits, on the air, that he brings them up too often. He keeps bringing them up. It’s giving monastic discipline, but secular — the practice is the practice, the practice does not get replaced because some new practice is trending on substack.

It dawned on me, somewhere around the fifth or seventh mention, that the consistency itself was a kind of argument. Not an argument for his particular questions, though if you stay with those questions for ten years they had better be good ones, and his are. The argument was about the structure of having two of them. You only get one life. You get to ask, what, a hundred big questions across a working lifetime, and most of those you’ll abandon halfway? Rutt picked two. He’s been working them for over a decade. He’ll be working them when he’s seventy. There’s a whole life shape to this that I had never seen modeled at close range before.

Which left me, slowly at first and then less slowly, with a question I had not particularly wanted: what are mine?

Not in a casual way — oh, what are some questions that interest me. Of course I have questions that interest me. I am a nerd, I have many questions, and I have nothing if not a long-standing reading list. The question Rutt’s repetition put to me was sharper than that. What are the two — give or take one — that you would be willing to fix for ten years? That you would mention on roughly half your conversations and not be embarrassed by your own consistency? That are worth narrowing your inventory to, in exchange for the depth you might get from staying with two instead of touring through forty? That is a different question and it does not have a flippant answer.

I have been ruminating on it for a few months. This post is what came out.

Rutt, briefly, for those who don’t know him#

Jim Rutt ran Network Solutions in the 90s and chaired the Santa Fe Institute in the 2010s. He is now retired in the way certain Americans of a certain generation are retired, which is to say he spends thirty hours a week running a long-form interview podcast where he reads the guest’s book, talks to them for two and a half hours, and asks better follow-ups than most academic peer reviewers manage. Gray beard, glasses, baseball cap, recording from somewhere in the Shenandoah Valley. The voice of a man who has explained the same thing to junior engineers many times and stopped pretending it was their fault for not getting it. He is allergic — allergic, in the medical sense — to lazy metaphysics. He has a running bit where he announces he is going to draw a pistol if anyone uses the word metaphysics without enough care. The pistol is imaginary. The bit is funny. He has been writing, over the last two years, a careful philosophical essay called A Minimum Viable Metaphysics, in which he tries to nail down exactly what commitments are necessary to do science. It is now on version 2.0. He has admitted in public that 3.0 is coming.

The pistol and the essay are not in tension; they are the same person. People who most hate the bad version of something are usually the people who end up writing the rigorous version.

His two questions#

The Fermi paradox you probably know in outline. Universe big. Universe old. Galaxy has a hundred billion stars. Even if a vanishingly small fraction produces intelligent life, the math says there should be a lot of intelligent life by now, and at least some of it should have left traces detectable across light-years. There are no such traces. The sky, as the astronomers say with admirable understatement, is silent.

Rutt got Fermi early — somewhere in the seventies, when he was a teenager, decades before Webb’s book existed (which would require time travel and a less minimum viable metaphysics than even he would tolerate). The book later gave the obsession a shape, but the obsession was already a tenant. The framing sentence — the one he uses to fire the whole pair — opens episode 258 with Webb himself: In Ruttian doctrine, it is why something and not nothing? In other words, why does the universe exist? — and, in the same breath: I believe that the answer to the Fermi paradox is the second-biggest question in science. It is that frame, ordered and hierarchical, that he slots by habit into half his episodes. Variations on it show up in dozens of others. He knows it’s a tic, and the tic, for him, is the practice.

The other one — the one he lists as the biggest, ahead of Fermi — is older and more open. Why something and not nothing. Why does the universe exist. This is the question he classifies as the biggest in science, and to which he has been devoting, over the last two years, a careful essay called A Minimum Viable Metaphysics. The essay is not an answer to the question — nobody has an answer to the question. It is Rutt’s attempt to identify the smallest possible set of philosophical commitments a person needs in order to do science, in the engineering sense of doing science — go to the lab, write a paper, predict a number, get the number within error bars of the measurement — without first having to answer the existence question. Most professional philosophers, when confronted with this kind of question, want to give you the entire palace: presentism or eternalism on time, identity theory or property dualism on consciousness, structural realism or pragmatism on physical objects, and on for thirty other questions you didn’t know you were supposed to have opinions about. Rutt’s move is to say I don’t need any of that. He wants the minimum. The current version is four commitments: there is a reality, the universe started asymmetric, some part of nature is lawful, and time involves genuine becoming rather than just a clock-index inside a static block. Four. Get out of bed. Do physics. Why something and not nothing remains unanswered. MVM is Rutt’s way of continuing to work in spite of the question, and, secondarily, is where he is showing, in minimum commitment, what about the question can be shown.

Where they stuck#

I was a nineties nerd the way you got to be a nineties nerd growing up in the interior of Brazil: TV Cultura and TV Escola via satellite dish (I was the only kid I knew who watched TV Escola outside of school, which wasn’t a matter of isolation — our gate stayed open all day and the yard was full of neighborhood kids all the time, I just sometimes preferred to be inside watching the show), Superinteressante magazine read cover-to-cover the afternoon it arrived in the mail (with particular affection for Luiz Barco’s column — a USP mathematician who also did math on public television, when didactic math on public television was a thing), dubbed reruns of Sagan’s Cosmos (the books I read in fragments, later), and a few hours a week on the forum of the Sociedade da Terra Redonda, running on phpBB, whose administrator was always asking for money to pay the server. STR was where things started getting too fringe to fit in Super — and it scratched the nerd itch much better than Super ever did. Hence Fermi: furniture in my head since I was twelve, installed by public TV and a phpBB forum.

Philosophy arrived through the same channels as Fermi, and through a few more. STR, underneath, was crossing metaphysics all the time — Fermi lived next to the simulation hypothesis, which lived next to personal identity and external-world realism, and the word philosophy not being hung on any of it didn’t stop it. TV Cultura and TV Escola had philosophy too, no sign on it, alongside everything else.

And around the house there was syncretism on every side, with the particularity that each part had arrived there on its own. My father had been a Catholic seminarian, left the seminary, and never paid any attention to the church again — not to change religion, just to take the subject off the agenda. My mother is from Seicho-No-Ie, itself a syncretic Japanese religion, and even so she would go to Catholic mass now and then. They both made a point of not baptizing any of their children because, in their view, that’s each person’s own choice. My grandmother lived in the house next door, with no wall between them — a practicing Catholic, and she would take me to processions. I went, and felt like the youngest boy in Graciliano Ramos’s Vidas Secas, watching all those people in the street paying attention to something I couldn’t quite figure out why they paid attention to, but reasoning: if they do, there must be a reason. Sometimes I would go to Francisco Beltrão, in the southwest of Paraná, to my paternal grandparents’ house — parents of my ex-seminarian father, who had stayed Catholic when he left — and we would pray the rosary every night at eight, the sun still firm in the sky as it is in December down there. I was growing up in Rondônia, one of the evangelical centers of Brazil, with each neighbor making a different religious choice. Inside the house, two parents on two different trajectories; next door, with no wall between, a grandmother on a third; farther away, in the southwest of Paraná, paternal grandparents on a fourth. Nobody intervening in anyone else’s path. The implicit lesson, without anyone needing to state it, was that a philosophical position isn’t a fixed identity, it’s a stop on a trajectory. Hence the permission to think for myself: it came from watching, without anyone needing to say, that nobody around me was standing still.

What made philosophy different from Fermi, in my biography, was when it got institutional spine. Before that there was my bookworm phase: two years boarding at the EAF in Colorado do Oeste, a federal technical school — full course in agroindustry, with a certificate I never bothered to pick up. The brand-new library stayed open until ten at night. It was books or the soap opera and pickup soccer in the courtyard. I didn’t have much trouble with that hard choice — except on Mondays, when I liked to watch Globo’s Monday prime-time movie on the shared TV in the courtyard. The other nights, reading. That’s how I found Jostein Gaarder’s Sophie’s World. It was a brick, and I checked it out from the library as a holiday was coming up — time to go back to Rolim de Moura. I hitchhiked as far as I could, I think I made it to Pimenta Bueno that way. Between one refusal and the next, sitting by the roadside, I’d open the book and read another chapter; when I heard a motor, I’d put my thumb out again. The book pushed me into other readings and then others. The third year at the EAF was optional; I was already tired of being away from home, so I went back to Rolim de Moura and finished high school at the Cândido Portinari state high school. That’s where I had an actual philosopher in front of the class: Everaldo Lins de Santana, trained in philosophy at UFPE. The norm, around me, was a teacher from another discipline giving philosophy class reluctantly, textbook in hand, the look of someone fulfilling required hours. Later still, three semesters of philosophy at UFMT — also with good professors. Existence, real, necessary: all three always asked me for a sideways second glance, and that’s from childhood, and it never went away. Hence why something and not nothing: even older furniture, installed before I had a word for the room. Home, EAF, Cândido Portinari, UFMT — each one furnished around it, without replacing.

I find both of these questions excellent. I want to say why, briefly, before saying why neither is mine.

Why they’re good questions#

The Fermi paradox is a probabilistic calibration exercise pretending to be an astronomy question. Every solution to it — the Great Filter behind us, the Great Filter ahead, the dark forest, the simulation, the rare-earth hypothesis, the zoo hypothesis, the they’re here and we don’t see them hypothesis — is a position on how to reason under massive uncertainty when your data set is one. Your prior matters. The evidence is sparse. You have to integrate over many parameters whose error bars are several orders of magnitude wide. That word is doing a lot of work when I say integrate: nobody knows how to do this honestly, and the whole field is, in effect, a community of smart people taking their best guesses out for a walk and seeing where they go.

The existence question — why something and not nothing — is, on the other hand, the question that most easily collapses into rhetorical emptiness. Why does the universe exist? is the kind of thing that shows up on backpacker T-shirts and in low-light TED talks, and in neither case does it usually get beyond the gesture. What makes Rutt’s version of the question different is not the question — it is what he refuses to do with it. Instead of piling big words on top of it until it looks heavy, Rutt subtracts: he pins down, with engineer’s parsimony, the minimum one is obliged to accept before even formulating the question honestly. What’s the smallest scaffolding I can put up and still hold the load? The philosopher’s traditional move is to keep adding things — every metaphysical position implies five more — until the whole edifice is too large to lift. Rutt’s move is the inverse. Tell me the four bricks. The rest is decoration. You may disagree about which four; you may want five, or three. But you’ve agreed to a game that has a chance of ending. Without that move, the existence question is Sisyphean by design.

Both questions also reward the kind of person who actually thinks about them, instead of having opinions about them. Fermi rewards the calibrated. The existence question, Rutt’s way, rewards the disciplined minimalist. They’re the kind of questions that, ten years in, you’ve gotten somewhere with — not all the way, never all the way, but somewhere — and the somewhere is itself a feature.

So they’re good. They’re old, they’re well-trodden, and they’re good. None of this is news to a nerd. The news, for me, was not the questions; it was that someone had picked these two and was staying with them.

What took me longer#

It took months of intermittent rumination — an elegant word for what would more decently be called avoidance — before I let myself write down what mine were. Months, for two reasons.

The first is that what are my two questions turns out to be a hard question to answer honestly. The easy version is what topics interest you most — for which I have a long, undisciplined answer that drifts across legal theory, philosophy of mind, complexity, probability, Brazilian institutional history, and at least three things I’d rather not list. The hard version is what questions would you fix and not abandon. Almost everything on the interest-list fails the not-abandon test. I read about something for a year and move on. The questions that actually survive that filter are smaller in number, and they are the ones I keep coming back to under the surface of whatever I’m reading at any given moment.

The second is that I was suspicious of the exercise. Picking two pivot questions sounded like the kind of LinkedIn-grade self-branding move that people make to seem deeper than they are. My two questions are: what is consciousness, and how can we build a more equitable society. No. That’s giving thought-leader. Rutt is not doing that — he genuinely cannot stop thinking about Fermi, he has been writing the metaphysics essay for two years, and his obsessions are confessional rather than performative. I had to make sure mine were too. The way I checked was simple: were these questions I’d been ruminating on for years already, without knowing they had a name? If yes, fine. If I was inventing them for the post, no.

The embarrassing thing is that they were not new. I had just failed to admit they were central. Written down as plainly as I can:

Are probability distributions real?

What is the best definition of reality?

Read them again. Both look smaller than they are. The first sounds like a question for an undergraduate statistics seminar; the second sounds like the kind of question one asks at a dinner party after the second bottle of wine. Their interest, for me, is in what each is hiding, and how each turns out to need the other to even get started.

The first one, on inspection#

The distribution question lands differently depending on which word you stress. Stress real and you have a tired ontological dispute about whether mathematical objects exist mind-independently — a fight going on since Plato that nobody has ever won decisively. Stress probability and you have a more interesting fight about whether probabilities describe the world (frequentist), describe our state of information (Bayesian), or describe an irreducible feature of nature (the question quantum mechanics keeps asking and refusing to answer). Stress distributions and you get the question I actually care about.

When we model some phenomenon as drawn from a distribution — heights from a Gaussian, particle decays from an exponential, queue waiting times from a Poisson — are we describing something about the distribution that is out there in the world, or are we using distributions as a bookkeeping convenience for our ignorance about underlying mechanisms that are, in fact, deterministic and individual?

I do not know the answer. Nobody knows. That’s the math not mathing. What I do know is that the question won’t leave me alone, and that the directions it pushes me — toward the foundations of probability, toward the interpretation of quantum mechanics, toward computational physics, toward whatever it is the Rosencrantz project is becoming — are the directions I find myself walking in when no one is watching. It is the place Rutt’s MVM 2.0 explicitly punts. He writes, in the Lawfulness section, “Both deterministic and stochastic interpretations of quantum mechanics remain viable. The experimental evidence does not yet distinguish between them conclusively.” He’s right not to commit; minimum-viable means leaving open what you can leave open. But the leaving open is exactly what I cannot put down. The frontier of his program is the start of mine.

The second one, which took longer#

The second one took three tries to write down honestly. I wrote it as what is reality? and crossed it out — too big, no traction, the kind of question a college freshman writes on a napkin and cannot read back later. I wrote it as is the world fundamentally physical? and crossed it out — old debate, well-trodden, nothing new I can add. I wrote it as what’s the relationship between mind and world? and crossed it out — same problem, slightly different costume.

What I actually wanted to ask, and what I finally wrote down when I let myself be honest, was this:

What is the best definition of reality?

Which sounds, on its face, even worse than the first three drafts. Wittgenstein would refuse the question — real is a word in ordinary use, it has its meaning from its use in language games, you don’t define it, you watch what work it does and leave it alone. I have some sympathy for that move. I also have a day job, where for almost twenty years I have made my living from the technical fact that words like good faith and public interest and reasonable and necessary do not, in fact, have stable meanings, and that my job is to negotiate, parecer by parecer, what they should be made to do in a particular concrete case. I am a working semantic engineer is one way to put it. Less generously, I’m paid to gaslight nouns into doing things they didn’t sign up for.

After enough years of this, when I sit down and look at a word like real — the most general, most overloaded, most contested term I encounter in any context — what I want to know is not what it means. I know it doesn’t have a single meaning. I want to know what job we would like it to do. Which is a Carnapian question more than a Wittgensteinian one — explication, Carnap called it, where you take a fuzzy ordinary-language concept and propose a sharper successor that does the same job better. Wittgenstein would withdraw permission and Carnap would hand it back. I am going with Carnap. The first question — are probabilities real — turns out to presuppose the second. You cannot answer whether a distribution is real until you know what real is for.

The shape of this#

Written down next to each other, the two questions do something I noticed only after I had put them on the page: they don’t sit in sequence. They argue.

The naive read is that one determines the other. You define real — that’s the second question — then you check whether distributions satisfy the definition. Clean order, second-then-first. But that is not what happens when I actually try to think about it. What happens is the reverse. I look at distributions doing absurd amounts of work — quantum mechanics, statistical thermodynamics, evolution, epidemiology, finance, machine learning, queuing theory, insurance, the whole inventory of things humans have built that actually work. That’s giving load-bearing math. And I look at serious people refusing to call them real. Frequentists who say a distribution is not an object, it is a limit of relative frequencies. De Finetti opening his treatise with probability does not exist. Non-realists about quantum mechanics insisting the wavefunction is a calculation tool, not furniture of the world.

The pressure that puts on the second question is not subtle. If a thing works that hard — predicts, calibrates, pays mortgages, vaccinates populations, builds reactors — and still fails the real filter, then what is the filter protecting? What does real refuse to grant, that distributions are doing without? Or, less charitably: is the definition of real we are using just too small?

The first question, by being empirically recalcitrant, forces the second to justify itself. The second determines the first, but the first also interrogates the second. The two questions don’t wait their turn. They argue with each other, and the argument is the content.

I don’t expect to answer either question. Neither does Rutt. The point of declaring pivot questions is not to be on a path toward answering them — it is to admit that you have them, that they organize your reading and your projects and your stray thoughts in the shower, and that the rest of what you do makes more sense if someone knows what they are. Here is where I have been stuck for years. Ask me how I’m doing on it. I’m not doing anything. I’m still stuck. I will be stuck on this at sixty. It is fine.

It is, in the end, a question about commitment. The world has too many interesting questions and one life is short. To pick two and stay with them is to refuse the rest. I have spent twenty years drifting from one fascinating-thing to another, and the drifting has not been wasted, but it has not produced what staying with two things for a decade would have produced. Rutt has why something and not nothing and Fermi — one question about why there is, and another about why, given that there is, we don’t see more. I have probability distributions and the definition of reality — one question about how the world behaves, and another about what we are demanding of a word that is holding up the rest. The two pairs don’t share a shape. Rutt’s is hierarchical, in ranking cadence, and the second is empirical corollary of the first under certain readings. Mine argues with itself, as I said. The interesting coincidence is not structural — it is that each of us picked two, and stayed with them.

What I’m sure of is that I should have written these down years ago.

For further reading#

• Jim Rutt, A Minimum Viable Metaphysics, v2.0 — the essay. Read this if you want to see what an engineer-philosopher’s commitments look like when written by someone who refuses to add anything that isn’t load-bearing.
• Stephen Webb, If the Universe Is Teeming With Aliens… Where Is Everybody? — the book that gave Rutt’s lifelong Fermi obsession a shape, and which lays out roughly seventy-five candidate solutions to the paradox. Even the bad ones are interesting.
• The Jim Rutt Show, EP 258 with Stephen Webb — the Fermi confessional. Rutt at his most open about the obsession.
• The Jim Rutt Show, EP 328 with Brendan Graham Dempsey — the metaphysics episode, where Dempsey interviews Rutt on his own program. The pistol joke is in there.
• Bruno de Finetti, Theory of Probability — for the subjectivist position on what probabilities are. De Finetti’s probability does not exist is the cleanest possible statement of the position my first question is trying to evaluate.
• Rudolf Carnap, Logical Foundations of Probability — for explication as a method. Read the introduction, skip the technical bulk; the introduction is what you want.
• Ludwig Wittgenstein, Philosophical Investigations — for the position Carnap is in tension with, on what it means to even ask what a word should mean.

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