Last night I rediscovered that, while lying in bed, I can always tell which side I'm facing towards. This is because, even if the room is dark and my eyes are closes, I have an innate ability to tell my left side from my right side.

That got me interested in if things were otherwise. What about a world where people cannot tell their 'left' from their 'right'? I am interested in how that world is different from ours. The reason is unimportant but here are two of my two favourites.

  1. The difference is internal: As a species they never evolved to notice the intrinsic difference between two orientations. Much like how real humans never evolved the natural ability to distinguish between different levels of ambient radiation in the environment.

  2. The difference is external. The geometry of the spacetime they live in is such that there is no intrinsic difference between 'left' and 'right'. I'm thinking something modelled similar in principle to 3-dimensional projective space $\mathbb{PR^3}$. That space is invariant by the reflection $x \mapsto -x$. Except these people live in a space that's invariant under all reflections.

How do the people in this world behave differently to us? How did they evolve? How do they build their roads and houses? What are the risks and solutions of getting lost on a stroll in the woods or the city? Where do the knives and forks go at the dining table. How does sound, colour and hearing work> How does writing work without an orientation?

This is of course an extremely broad question. But also a fascinating one.

Edit: This question was deemed to broad. I have opened a narrower question here.

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    $\begingroup$ I don't think you get a universe that can evolve life if there is invariance under all reflections, the universe has a handedness. $\endgroup$ Commented May 22, 2017 at 23:21
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    $\begingroup$ This is definitely overly broad, and I'd recommend narrowing it down. Consider asking simply about a lack of chirality at the smallest levels. $\endgroup$
    – HDE 226868
    Commented May 22, 2017 at 23:37
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    $\begingroup$ If star fish were sentient, I wonder if they would care about left or right, or would radial orientation matter far more to them? $\endgroup$ Commented May 22, 2017 at 23:39
  • $\begingroup$ I think you might be interested in relative direction, as well as left-right confusion and topographical disorder, OP. I tried finding this thing about a boy incapable of sensing up from down. His father is a teacher. Needless to say, he couldn't survive on his own. $\endgroup$ Commented May 22, 2017 at 23:52
  • $\begingroup$ It may not look like left and right, but if there is physical shape to sapient beings in a 3-d world, there will be some way they distinguish direction relative to self. "Everyone knows you should teach distals to write proximally. If you don't, they won't be able to function properly in society...." If there are sapient beings without physical form, then the terms might more likely indicate nearness vs. farness relative to other beings/objects than themselves, or x degrees of entanglement between selves/others, or perhaps how much solubility there is between selves/others. $\endgroup$
    – N2ition
    Commented May 23, 2017 at 2:59

2 Answers 2


Strangely enough, this relates to me personally. My grandmother did not instinctively know her left from her right. She had to consciously think about it. If someone yelled for her to "turn left" she had to stop, and then turn. In a car she knew that the door nearest to her was the left and the passenger side was the right, and that's what she used in order to know which way was which. Unlike you, in the dark, she didn't have that innate proximal ability.

This inability was passed down to me. I had the same problems that she did for years until an accident. But I can speak to how navigating the world was different for the two of us.

Neither of us could quickly follow orders to turn in a specific direction. We had to stop and consciously think about it. Directions that worked better were things like, turn towards the pharmacy or landmark X, rather than turn left. Without cues such as the inside of a car and where the door was located in relation to left and right, we'd be unable to tell, and actually had to try and work it out. She used her wedding ring as a quick way to tell, but if she'd left it off, she took longer.

Yes, she was a person who could not tell her left from her right easily, in a world where those concepts exist, but I am hoping that her experiences and mine are helpful for how the world would be navigated by such a person.

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    $\begingroup$ @Rekesoft Absolutely, if there's a chasm we'd see which side it was on. I know it doesn't exactly fit, but if the OP is building a species that doesn't have the left/right concept, it's a good place to start. $\endgroup$ Commented May 23, 2017 at 14:47
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    $\begingroup$ I have a bit of this as well, I used my watch to have a reference on hand, as it were, and a lot of rote learning. I always attributed it to having some ambidextrous traits - after all, if either hand can do something, it is less important to know which hand does the something. And it is easier to map external directions left and right onto the impulse-and-instinct which already knows strong side and weak side - otherwise I'd guess it would be more like compass directions where most people need rote learning and/or an external nudge to orient off of, each time. $\endgroup$
    – Megha
    Commented May 24, 2017 at 15:36
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    $\begingroup$ @PeterCordes If we see something and want to turn towards it, then we'd be fine. We didn't mentally make a plan to to turn a certain way, just towards a CERTAIN THING. So the plan would be, turn towards the country store when you get to the end of the road, not turn towards a particular side. If the store and any sign of it was gone, we'd have no idea which way to turn. $\endgroup$ Commented May 27, 2017 at 21:54
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    $\begingroup$ @PeterCordes Any directions written for her that said turn left or right at street x, she'd have to look for the cues. Like the fact that right was the passenger side, and left was the door closest to her. Arrows worked on written directions, but she had to look at the directions at the time she was turning. So the answer to your question is yes, she'd have to physically look to see it. $\endgroup$ Commented May 29, 2017 at 2:39
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    $\begingroup$ @ErinThursby - It always made sense to me as a cause for my need for cues, even when others thought I was just being slow to learn. I also ended up mostly right-handed, though I don't know if that was innate or just the default taught... though even then, it still showed in little errors like, when using my watch to tell hands, I put it on my right hand - since that's the one I need to know, right? - and didn't figure out why people usually used their off hand for watches (snagging when reaching into) until switching would have meant a lot of starting over. It takes thinking to figure out $\endgroup$
    – Megha
    Commented May 31, 2017 at 4:04

There's not many cases in 3 space where your left and right don't matter. In fact, there's few cases where the exact direction of your vectors don't matter. However, it may be possible to create an environment where an intelligent species has intentionally crafted a world where it is unnecessary to distinguish them.

We often say an action has an equal and opposite reaction, but what if you took it to an extreme. What if you had a society that structured themselves such that every time they wanted to do something to the left, they also wanted to do something to the right. Let's say they're hungry, and there's a food vendor to the left. They might not even think of paying the food vendor for some food until there is also a corresponding lemonaide stand on the right. Then, they would buy some food, and invariably buy some lemonaide as well. They might not even think anything of it if they were well indoctrinated.

Doing this with the left and right may be a bit strange, but there's interesting implications if they instead always do things up and down at the same time. If, when giving taxes upwards to the state, they give alms downwards to the poor, you create a fascinating social structure.

Another interesting place this appears is in martial arts. There are many martial arts which seek to have explosive energy in all directions. In these, the goal is to be able to have a trigger that says "go" and all parts of your body attack outwards to the best of their ability. In these, you are aware of your left and right, but one of the ideals is to not need to concern yourself with them, because in combat, you may not have time to think about left and right. You need to strike your opponent no matter where they are.


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