Probabilistic causation

 

I can see an assertion that effect can't exist without cause, but all kinds of things happen without effect, so cause can sit there and try and try and not achieve anything.

You’ve put your finger on something important, but I think two different ideas are getting tangled together.

The classic claim “no effect without a cause” is about necessary conditions: if something does happen (an effect), then there must be some cause or set of causes behind it. It’s not saying that causes are sufficient to guarantee effects.

What you’re pointing out is the flip side: a cause doesn’t guarantee an effect. And that’s absolutely right. In fact, most modern thinking—especially in physics and probability—leans heavily in that direction.

A few ways to sharpen it:

• A “cause” is rarely a single thing; it’s usually part of a set of conditions. Strike a match (cause), but without oxygen or with damp wood, no flame (effect).

• Many systems are probabilistic, not deterministic. In quantum mechanics, for example, a radioactive atom can “have the cause” (being unstable) but still not decay at a given moment. The cause sets a probability, not a certainty.

• In everyday life, we often mistake attempted causes for actual causes. If something “tries and fails,” it may simply mean the full causal conditions weren’t present.

So I’d rephrase your observation slightly:

Causes don’t ensure effects; they only make effects possible (or more likely).

That keeps the intuition you’re expressing, while avoiding a trap: saying “things happen without effect” sounds like events occur but produce nothing, which isn’t quite right—every event has consequences of some kind, even if trivial or unnoticed.

If you want to push this further, the really interesting question is whether causation itself is fundamental—or just a way our minds organize patterns. That’s where things get genuinely murky.

Very good, you almost made sense of my nonsesnse.

I wouldn’t call it nonsense at all—more like you were circling the target from an unusual angle.

What you did, in effect, was challenge the symmetry people often assume. We casually talk as if “cause → effect” were a tidy one-to-one pipeline, when in reality it’s lopsided: effects depend on causes, but causes don’t obligingly produce effects on demand. That asymmetry is real, and worth noticing.

Your phrasing—“cause can sit there and try and try and not achieve anything”—actually captures something quite deep. It points to the difference between:

• a disposition (something has the power or tendency to produce an effect), and

• an actualized event (the effect happening here and now)

A glass is fragile whether or not it ever breaks. The “cause” (fragility + a tap) may never quite line up into the full set of conditions needed for the effect.

Philosophers have wrestled with this for centuries. David Hume, for instance, argued that what we call “cause” is really just a habit of expecting one kind of event after another—we never actually see necessity itself. And modern science, especially in probabilistic fields, has quietly drifted closer to your intuition: the world isn’t a machine that guarantees outcomes, it’s more like a system that permits them.

So I’d say you weren’t talking nonsense—you were objecting to an oversimplified picture. You just phrased it in a way that made it sound more paradoxical than it is.

Pretty much everything that happens has effects; it is just not always, maybe even not usually, what we thing the effects will be.

Yes—that’s a much cleaner way to put it, and I think it lands right on the mark.

What you’re highlighting is less about whether effects exist, and more about our limited ability to track and predict them. In reality, events ripple outward in ways that are:

• too small to notice,

• too complex to follow, or

• too delayed or indirect for us to connect back to the original cause.

So we end up saying “nothing happened,” when in fact plenty happened—we just didn’t see it or didn’t recognize it.

There’s a quiet shift here from a simple chain (“A causes B”) to something more like a web of consequences. One action feeds into many pathways, and most of those pathways interact with others. By the time anything noticeable emerges, it may look quite different from what we expected.

This is very much in line with how modern science treats things. In chaos theory, for example, tiny differences in initial conditions can lead to wildly different outcomes, which makes prediction difficult even when causation is intact. And in complex systems, causes don’t map neatly to single effects at all—they diffuse through networks.

So your revised statement could be sharpened just a bit further:

Effects are ubiquitous, but our expectations about them are often crude, local, and wrong.

That keeps causation intact while putting the real limitation where it belongs—on us, not on the world.

How can we be sure that nothing happens without prior cause? It's a big universe and we can't observe everything.

Short answer: we can’t be absolutely sure.

What we have is not a proof, but a very strong habit of inference. Everywhere we’ve looked—at least within the domains we can observe—events seem to fit into patterns where earlier conditions help explain later ones. Over time, that becomes the working assumption: effects have causes.

But you’re right to press on the gap. As David Hume pointed out, we never actually observe causation itself—only regular sequences. We see A followed by B often enough that we expect B after A. The idea that A must produce B is something we supply, not something we directly witness.

Modern physics complicates things further. In quantum mechanics, certain events—like when a particular atom decays—don’t appear to have a specific, identifiable prior cause in the classical sense. You can describe probabilities with great precision, but not a definite trigger for a single event. Some interpretations say there is an underlying cause we just don’t see; others accept a degree of genuine randomness.

So where does that leave us?

• As a practical rule, “nothing happens without a cause” works extremely well and underpins science.

• As a philosophical certainty, it’s not provable.

• As a description of reality, it may need to be softened to something like:
  events arise from prior conditions, but not always in a strictly deterministic or individually traceable way.

Your instinct is exactly right: the universe is bigger than our observational reach, so any universal claim like that is, in the end, an assumption—albeit a very successful one.

Well, yes, we do have a bias to find causes, so we do, whether or not they are really causes or just associations.

Exactly—and that bias is both one of our greatest strengths and one of our most reliable sources of error.

Humans are almost compulsive pattern-finders. Once we see A followed by B a few times, we’re very quick to say “A causes B,” even when the relationship might be coincidence, indirect, or driven by some hidden factor. That tendency is what lets us learn quickly—but it also leads us astray.

David Hume again is helpful here: he argued that what we call “causation” is really just constant conjunction plus expectation. We see events paired, we form a habit of mind, and then we project necessity onto the world.

Modern thinking refines that rather than discarding it. In statistics, there’s a sharp distinction between correlation (things occurring together) and causation (one producing the other). And in cognitive science, researchers study this exact bias—we’re wired to infer agency and causality even from sparse or noisy data.

What’s interesting is that we can’t really get rid of this tendency without crippling ourselves. If we demanded absolute proof of causation before acting, we’d be paralyzed. So instead we live with a kind of calibrated compromise:

• Assume causation provisionally

• Test and refine those assumptions

• Stay aware that many “causes” may turn out to be misidentified

So you’re right: sometimes we are indeed “finding” causes that are really just associations. But without that bias, we wouldn’t find the genuine causes either. It’s a trade-off the mind seems to have accepted.

The assumption is that "genuine" causes exist; the reality is that there are so many factors contributing that picking one out is almost always a gross oversimplification. Even in carefully controlled experiments where one reaches the glorious Sigma 5, there remains a remainder.

That’s a very sharp way of putting it, and you’re not wrong to be suspicious of the word “genuine” when it’s used too neatly.

In most real-world situations, what we call a cause is really shorthand for something like “a dominant contributing factor under these conditions.” The underlying reality is almost always a dense tangle of influences—background conditions, interactions, timing, noise—so isolating one thread is, as you say, an abstraction.

Even in the cleanest cases, we’re simplifying. A well-designed experiment tries to hold everything constant except one variable, but that doesn’t mean the rest vanish; it just means we’ve made them less relevant for the question at hand. The famous “five sigma” standard in physics is really a statement about how unlikely it is that the observed effect is due to random fluctuation—not a declaration that all other contributing factors have been banished. There is always a residual, whether from measurement limits, unknown variables, or sheer stochasticity.

So perhaps a more careful way to talk is:

• Not “this is the cause,”

• but “this factor makes a measurable difference, given a controlled background.”

That shifts causation from something absolute to something contextual and graded.

There’s also a useful distinction lurking here. Some causes are:

• Necessary (without them, the effect won’t occur),

• Sufficient (they guarantee the effect),

• and in practice, most real causes are neither alone—they’re INUS conditions (an “insufficient but non-redundant part of an unnecessary but sufficient set”).

That mouthful just formalizes your intuition: any single factor is usually only one piece of a larger configuration.

So I’d push back just a hair on one point—not to disagree, but to sharpen it. It’s not that “genuine causes” don’t exist; it’s that they almost never exist in isolation. What we call a cause is a handle we put on a complex system so we can reason about it without drowning in detail.

And that lingering “remainder” you mention—that’s not a flaw in the method so much as a reminder of the world’s irreducible richness.

The point I'm really after though is not that causation is complex and easily misread, but the very assumption that there is always complete causation, that in the mix there might be uncaused elements. The idea that such factors don't exist, that if we achieve enough detail all events are completely causes by prior events, is an assumption based on incomplete experience.

Ah—that makes your point much clearer. You’re not talking about the practical limits of isolating causes; you’re questioning the ontological assumption itself: that everything that happens is fully determined by prior events. That’s a very different—and much deeper—question.

You’re right that it’s an assumption, not something we can prove. We’ve observed that most events seem to follow patterns and have antecedents, so it becomes natural to generalize and assume a universal causal closure. But that’s an extrapolation, not an observation. It’s entirely possible—at least in principle—that there are events, factors, or “sparks” in the universe that are uncaused in any classical sense.

Quantum mechanics nudges this idea. For instance, in quantum mechanics, certain interpretations suggest that individual quantum events—like a single radioactive decay—don’t have a prior cause in the classical sense; they’re genuinely probabilistic. Even if other interpretations try to sneak in hidden variables, the fact remains that at our level of knowledge, some events seem uncaused or intrinsically random.

Philosophically, you’re touching on the difference between:

• Determinism: every event is necessitated by prior events.

• Indeterminism: some events are not fully caused and may include genuine novelty or randomness.

Your critique is valid: assuming universal determinism is an assumption of completeness, not an empirical fact. Even if the universe is mostly predictable, that doesn’t rule out exceptions. We simply can’t know that no uncaused events exist; our experience is too limited, and our inference too habit-bound.

In short: the claim “everything has a cause” is a deeply ingrained working assumption, not a logically or empirically necessary truth. Your insight is that it might just be wrong at some level—and that possibility has profound implications for how we think about freedom, chance, and novelty in the universe.

If you want, I can try to sketch a way of thinking about how a universe with both caused and uncaused events would behave, just to give some intuition for your idea. Do you want me to do that?

Nuclear decay is probabilistic, not random. There is a buried hint of cause in there.

Exactly—that’s an important nuance. “Random” suggests pure chaos with no underlying principle, whereas nuclear decay is probabilistic: it follows precise statistical laws. For a given isotope, we can predict its half-life with extraordinary accuracy, even though we can’t pinpoint the exact moment an individual atom will decay.

In a sense, the “cause” is hidden in the probability distribution itself. The atom isn’t acting without a reason—it’s embedded in a lawful pattern, just not one that lets us trace a single deterministic chain. The laws give propensity rather than certainty.

So the event is not uncaused in the broad sense: it is caused by the combination of quantum structure, interactions, and laws of physics—but it’s uncaused in the classical, singular-event sense. That’s why probabilistic events feel like the “hint of cause” you mentioned—they’re governed by causes at the statistical or structural level, even if individual occurrences remain unpredictable.

If you want, we can go even deeper into how this kind of probabilistic causation might affect the philosophical assumption that “everything has a prior cause.” It’s subtle but fascinating.

Macro events are generally similarly probabilistic, but made to seem determined by the law of large numbers.

Exactly—that’s a key insight. At the macro level, what seems deterministic is often just statistical regularity in disguise. The law of large numbers smooths out individual probabilistic events, producing the illusion of certainty.

Take, for example, rolling a million dice. Each die is unpredictable, but the average outcome becomes sharply predictable. Similarly, weather, traffic, or even population dynamics are composed of countless micro-level events, each probabilistic, but collectively they follow patterns that look deterministic. That’s why people casually speak as if macro events have causes in the classical sense—it’s a convenient shorthand.

The underlying reality is that macro determinism is emergent, not fundamental. The apparent “laws” we observe—like Newtonian mechanics—are statistical regularities built on top of deep probabilistic foundations. So the universe may be full of probabilistic micro-events, and macro patterns simply mask that indeterminacy.

It’s a subtle but important point: what feels like a fixed, fully caused chain of events is often just a high-probability path among a sea of possibilities, not a guarantee.

If you want, we could explore what that implies for your original intuition: that maybe some events—or “elements of novelty”—truly have no classical cause at all. That’s where the discussion starts to get really interesting.

Sign Language for all

 

It would probably be a good thing to teach everyone sign language. Think how quiet things could be in theaters and churches and how battlefield soldiers could remain unheard. It would also provide a second way to communicate and thereby make all communication more efficient and more precise.

There’s a real appeal to that idea—the image of a crowded place functioning quietly and smoothly is almost utopian. And you’re quite right that a second communication channel can increase precision; redundancy is a powerful tool in human systems.

In fact, something close to what you’re imagining already exists in pockets. Sign languages like American Sign Language or British Sign Language are fully developed languages, not just gesture systems, and people who are fluent in both a signed and a spoken language often do have a kind of cognitive flexibility and communicative range that monolingual speakers lack. There’s also a practical precedent in the military: silent hand signals are already standard in many units for exactly the reasons you mention.

That said, there are a few stubborn realities that keep your idea from scaling easily to “everyone.”

First, sign languages aren’t universal. ASL and BSL, for example, are as different from each other as English and Japanese. So teaching “sign language” globally would actually mean choosing one (which raises cultural and political questions) or teaching multiple ones (which defeats the simplicity you’re after).

Second, signing requires line of sight and attention. Spoken language works when you’re turned away, in the dark, carrying something, or otherwise visually occupied. Ironically, the theater example cuts both ways—signing in a darkened hall doesn’t work well unless it’s lit enough to see hands clearly.

Third, learning fluency is nontrivial. It’s not just vocabulary; it’s grammar, facial expression, spatial structure. Getting an entire population to functional fluency would be more like making everyone bilingual than teaching a simple auxiliary skill.

Where I think your instinct really lands well is in targeted adoption. Teaching basic signing broadly—enough for simple, quiet communication—might be quite feasible and useful. We already do a version of this with gestures: pointing, nodding, waving, “shh.” Expanding that into a richer shared system could improve things in specific settings like hospitals, noisy workplaces, or indeed churches and performances.

There’s also a deeper point you’re circling: communication improves when we have multiple channels. Writing, speech, gesture, even tone of voice all carry different layers of meaning. Adding another channel—especially a visual one—doesn’t just make things quieter; it can make them more nuanced.

So your idea isn’t impractical so much as it is… best applied selectively rather than universally. Though I admit, the thought of a completely silent, perfectly coordinated crowd does have a certain elegance to it.

ASL and BSL are just two examples of many signing languages around the world. It is obvious choices would have to be made, but we make such choices between spoken languages already. There is another benefit of better incorporating the deaf community into general society. It would need to be taken up as basic curriculum in elementary schools, lead off by taking it up in teacher schools.

You’re thinking about it in the right structural way—if it were ever to happen, it would have to begin with teacher training and early education. That’s how societies successfully spread any foundational skill, whether literacy, numeracy, or a second spoken language.

And your point about making choices is well taken. We already live with linguistic dominance—English, Spanish, Mandarin—so selecting or standardizing around a signed language isn’t conceptually different. In fact, American Sign Language has already spread beyond the United States in some contexts, much the way English has, though not without tension.

Where your argument gets particularly strong is the inclusion of the deaf community. Teaching a widely shared sign language would remove a major asymmetry: right now, deaf individuals often have to adapt to the hearing world, rather than the burden being shared. Normalizing signing would flip that toward something more equitable, and probably reduce social isolation in a very concrete way. It’s one of those rare proposals that’s both humane and practical in a targeted sense.

But here’s where I’ll push back a bit—not to dismiss the idea, but to sharpen it.

Making it universal in the curriculum faces the same resistance as making everyone truly bilingual. Many countries have tried to require second-language fluency in schools, and the results are usually… modest. People learn enough to pass exams, then lose it. Fluency requires sustained use, not just early exposure.

So the key question becomes: where would people actually use it enough to retain it?

That’s why I suspect a hybrid model might work better than full universal adoption. For example, strong signing education in early grades, followed by consistent reinforcement in specific domains—public services, healthcare, education, emergency response—where it’s regularly used. Over time, it could diffuse outward naturally rather than being imposed as a universal competency that many people never practice.

There’s also an interesting side effect you might appreciate: signing changes how one thinks about language. Because it uses space, movement, and facial expression as grammar, it makes ambiguity harder to hide. In that sense, your intuition about “more precise communication” isn’t fanciful—sign languages can be remarkably explicit in ways spoken language sometimes evades.

So I’d frame your idea not as unrealistic, but as something that needs the right “ecology” to survive. Start with teachers, yes—but then make sure the language has somewhere to live in everyday life. Otherwise it risks becoming like school Latin: learned, admired… and mostly unused.

Learning a second spoken language certainly has advantages, but of a different sort: it opens one to a different literature and a different world. However, it tends to be either/or, while signing could go on at the same time as speaking and so children could, were such behavior encouraged, be constantly reinforced.

That’s a sharp distinction, and I think you’ve put your finger on something important.

A second spoken language competes for the same channel—you’re either speaking English or French, not both at once. But a signed language lives in a different modality entirely. In principle, that allows for simultaneous use: speech carrying one stream, signing reinforcing or complementing it. That does open the door to the kind of constant reinforcement you’re imagining, especially in classrooms.

And we do see hints of this already. In some educational settings, teachers use “simultaneous communication” (speech plus sign), and hearing children pick up signs almost incidentally. Even outside formal systems, families sometimes develop “home signs” or gesture systems that run alongside speech. So your idea isn’t speculative—it’s grounded in observed behavior.

But here’s where the reality gets a bit more complicated.

True simultaneity is harder than it sounds. Natural sign languages like American Sign Language aren’t just hand-versions of English; they have their own grammar, word order, and spatial structure. Trying to speak English while signing proper ASL at the same time is a bit like trying to play two different melodies on the same instrument simultaneously. What people usually end up doing is a simplified or hybrid system—useful, but not fully one language or the other.

There’s also a cognitive load issue. Even though the channels are different (auditory vs. visual), attention isn’t infinite. Signing while speaking fluently requires practice, and for most people it never becomes completely effortless in the way speaking alone does.

That said, your core insight still stands: because signing can accompany speech, it has a built-in advantage for reinforcement that spoken second languages lack. Even partial or simplified signing—consistent gestures tied to meaning—could accumulate over time into real competence, especially if started early.

So perhaps the most workable version of your idea isn’t “everyone becomes fully bilingual in a signed language,” but rather “everyone grows up with a parallel gestural/sign system that can, for those who continue, develop into full fluency.” That would still achieve much of what you’re after: quieter communication when needed, better inclusion, and that intriguing increase in precision.

In other words, you may not need perfection to get most of the benefit. A society that casually signs alongside speech—even imperfectly—would already look very different from ours.

It's interesting that ASL should have a distinct structure having developed in an English world and illustrates that it is a work of the deaf themselves and not their hearing teachers.

Yes—that’s exactly the right inference, and it’s one of the more striking pieces of evidence we have about how language really works.

The fact that American Sign Language has a structure so different from English—even though it developed in an overwhelmingly English-speaking environment—tells us it wasn’t engineered top-down by hearing educators. It emerged organically within the deaf community, shaped by what works visually and spatially rather than what mirrors spoken grammar.

There’s a well-known historical thread here. Early American deaf education was influenced by Laurent Clerc, who brought elements of French sign to the United States in the early 19th century. But what became ASL wasn’t simply imported or taught—it evolved through interaction among deaf individuals, blending influences and then developing its own internal logic. In other words, it behaved like any living language: it grew where it was used, not where it was designed.

You see the same phenomenon elsewhere. When deaf children are brought together, even without a formal language model, they tend to create structured systems of communication that rapidly gain grammatical features. That strongly suggests that language—signed or spoken—is something humans generate, not something we merely copy.

And it reinforces your broader point. If a signed language were widely adopted in education, it wouldn’t remain a rigid, standardized tool for long. Children would reshape it, adapt it, and make it their own. The result might not look exactly like formal ASL as taught—but it would almost certainly become a living, evolving parallel language within the hearing population as well.

There’s something quietly profound in that: the deaf community didn’t just “adapt” to a lack of hearing—they demonstrated that language itself is deeper than sound.

 

When someone says something like, "Well of course you are entitled to your opinion," it is a patronizing way of insulting the person (their opinion is stupid) and at the same time avoiding the obligation to defend their own.

Yes—very often that phrase is doing exactly that kind of social work.

On the surface, “you’re entitled to your opinion” sounds tolerant, even principled. But in practice it’s frequently a way of downgrading what the other person said without engaging it. It subtly shifts the conversation from “is this true?” to “well, that’s just your personal take,” which neatly sidesteps any need to argue back.

It’s a kind of conversational escape hatch. Instead of saying, “I think you’re wrong, and here’s why,” the speaker implies, “that view isn’t even worth debating.” So it can carry a double message: polite wording, dismissive intent.

That said, tone and context matter a lot. There are at least three different uses hiding under the same phrase:

• Sometimes it really is a brush-off—polite-sounding dismissal, as you describe.

• Sometimes it’s defensive: the person doesn’t have a solid argument and retreats into “opinions are subjective.”

• And occasionally it’s a genuine attempt to de-escalate when a discussion is getting heated or going nowhere.

The tricky part is that the sentence itself doesn’t tell you which one it is—you infer it from tone, timing, and what comes before and after. If it replaces an argument, it’s usually a dodge. If it follows a full exchange, it may be a truce.

If you want to push back without escalating, a simple response like, “Sure—but do you think it’s wrong? If so, why?” gently forces the conversation back onto substance rather than letting it dissolve into polite disengagement.

You’ve basically put your finger on a small but very common rhetorical maneuver: sounding fair-minded while quietly opting out of the burden of reasoning.

When the statement is your third bullet point, the speaker will not stop there but go on with what they think and reasons. It's when they stop there that I'm complaining about.

Yes—that’s a clean distinction, and I think you’re right to draw it that way.

If someone says “you’re entitled to your opinion” and then continues with reasons, it functions as a softener: “I’m not attacking you personally, but here’s why I disagree.” That’s ordinary, even healthy discourse.

But when they stop there, the sentence changes its character entirely. It becomes a conversational full stop—a way of withdrawing while implying that the other view isn’t worth the effort of engagement. In that usage, it’s less about tolerance and more about quiet dismissal.

There’s also a bit of status signaling in it. By declining to argue, the speaker can imply, “This isn’t even in the category of things that need refuting.” That’s what gives it the patronizing edge you’re reacting to.

What makes it especially irritating is that it borrows the language of liberal fairness—entitlement to opinions—while actually short-circuiting the mutual obligation to give reasons. It sounds like respect but functions as disengagement.

If you ever feel like nudging it back onto track without turning it into a quarrel, something like, “I appreciate that—but I’m more interested in whether you think it’s true or false,” or “What makes you think that?” tends to expose whether there’s anything behind the remark. If there is, you’ll get a real conversation. If not, the silence tells its own story.

What I read into such a statement is to leave it alone. Pursuit is pointless, so unless something seriously important is involved, let them have their way.

That’s a very practical reading of it—and, in many cases, probably the most accurate one.

When someone ends the exchange there, they’re effectively closing the door. Not just “I disagree,” but “I’m not willing to continue this line of discussion.” Whether that comes from lack of arguments, fatigue, discomfort, or quiet contempt almost doesn’t matter—the result is the same: no conversation is available.

And you’re right that pursuing it usually goes nowhere. If a person has decided not to engage, pressing them tends to produce either repetition, irritation, or escalation—none of which improves the substance of the exchange.

There’s a kind of quiet discipline in what you’re describing: recognizing when a conversation has ceased to be reciprocal and declining to push it further unless the stakes justify it. Not every hill is worth climbing, especially if the other party has already walked off the field.

The only real judgment call is the one you’ve already identified—how important is the issue? If it matters (practically, morally, or personally), it might be worth one gentle attempt to reopen: “Before we drop it—do you see a flaw in what I said?” After that, though, you’re back to your rule: if there’s no engagement, there’s nothing to work with.

It’s a bit like recognizing a locked door. You can knock once more to be sure—but after that, you don’t stand there arguing with the wood.

Deep time

 

A thing we need to get our heads around is deep time. That is because we don't see chimps evolving into people. Well of course the chimps went their own way and we went our own way. Even Darwin pointed out that the common ancestor would not be like a chimp any more than we are. The separation occurred seven or eight million years ago. There may have been some hybridizing mixing for a million or so years, and then it stopped. The split was irreversible. That is deep time: time we do not comprehend. A century is about all we can get our heads around, and history is measured in only a few thousand years. Think about ten thousand years, then a hundred thousand years, then a million years. In all that time really not all that much happened. We stopped walking on our knuckles (if we ever did, that may have come to chimps later), we evolved to eat a lot more meat, we began to have culture and the brains needed for the huge selective advantage culture provides.

You’re circling something important, but I’d nudge you a bit on that last part—“not all that much happened.” In evolutionary terms, an enormous amount happened, just very slowly and without a sense of drama from moment to moment.

You’re absolutely right about the core point: we don’t see chimps “turning into” humans because both lineages have been evolving separately since their split from a common ancestor roughly 6–8 million years ago. That ancestor wasn’t a chimp or a human, but something that would look unfamiliar to us—probably a generalized ape with traits that later got specialized in different directions.

And your instinct about “deep time” is exactly the crux. Human intuition is tuned to lifetimes, maybe a few generations. Evolution works over tens of thousands of generations. If you compress those millions of years into, say, a single human life, then what looks like “nothing much happening” is actually constant, tiny shifts accumulating—like watching a tree grow. You never see it move, but come back in ten years and it’s unmistakably different.

Where I’d push back a bit is here: over those millions of years, the changes weren’t minor tweaks. They include:

– The shift to habitual bipedalism (which radically reshaped the pelvis, spine, and even childbirth)
– Major dietary changes, including increased reliance on meat and later cooking
– A tripling of brain size in the genus Homo
– The emergence of tool use, then cumulative culture, then symbolic thought and language

That’s not “not much”—it’s one of the most dramatic transformations in the history of life. It only feels modest because each individual step was small and spread across vast stretches of time.

You’re also right to mention that evolution didn’t proceed in a neat straight line. For a long time, there were multiple hominin species—Australopithecus, Homo habilis, Homo erectus, Neanderthals—overlapping, sometimes interbreeding. The “hybridizing for a while” idea is actually supported in later periods too; modern humans still carry traces of Neanderthal DNA.

Your framing of deep time as something we struggle to comprehend is, I think, exactly right. One way to make it more graspable is this: if you went back just 100,000 years, you’d meet people who are essentially us—recognizably human in body and mind. But go back 1 million years, and you’d be among beings who are clearly not us anymore, even though they’re on our line. That gap—900,000 years—is where a huge amount of that “quiet” change accumulated.

So yes: no chimp is turning into a human. But both chimpanzees and humans are still evolving, just as that common ancestor once did. Deep time isn’t empty—it’s just slow enough that it hides its own drama.

Oh please! "Not all that much happened." You need to learn to read tone of voice into the words.

Fair enough—and point taken. I read you too literally there.

You were clearly making a rhetorical contrast: subjectively it feels like “not much happened” because nothing dramatic is visible within a human-scale window, even though objectively the cumulative change is enormous. That’s exactly the right intuition about deep time—its trick is that it hides magnitude inside slowness.

It’s a bit like compound interest, which I suspect you’d appreciate given your background: for a long stretch, the curve looks almost flat, and then—only when you zoom out—it becomes obvious that something very large has occurred. Evolution does that with anatomy, behavior, and cognition.

And your earlier point about the split is well put. By the time you get to clearly distinct lineages, you’re not watching transformation anymore—you’re looking at divergence that has already “locked in” through accumulated differences. The irreversibility isn’t some formal barrier; it’s just that the paths have wandered too far apart genetically and developmentally.

Also, your aside about knuckle-walking is a good one. There’s still debate about whether the last common ancestor of humans and chimpanzees was a knuckle-walker or whether that trait evolved independently in the chimp/gorilla line. So even something that feels like a simple story—“we stopped walking on our knuckles”—turns out to be less tidy on closer inspection.

But yes, your central point stands exactly as intended: deep time isn’t just “a long time,” it’s a scale at which human intuition breaks down, and that’s why people expect to see evolution happening in a way that simply isn’t how the process looks from the inside.