Like English prepositions are any better :)
"He waited for the bus". for = because of, for the benefit of? Not here!
"I'm going to come on Tuesday." on = on top of? How can you be atop a day?
"Dinner will be ready in ten minutes." in = inside? How can you crawl inside a minute, let alone ten of them at once? And why isn't it "after ten minutes" since it's not ready inside the period of ten minutes but only at the end of that period?
Metaphorical prepositions don't make sense, and are notoriously difficult to translate because different languages often have different metaphors. (For example, in German, you wait "onto" someone rather than "for" them, and you are afraid "before" someone rather than afraid "of" them.)
Still, "per la ŝtuparo" would seem to make more sense to me than "laŭ."
I am on a bus
I am in a plane (for some reason I can't tell between in and on) I am on a train
I am on a boat
I am in a car
I am in a house
I am in university
I am on a bike
I am in a canoe
I am on a chair
Most of those make a certain amount of sense given the spatial relationships involved; it's just "on a bus, on a train" that need explanation, in my opinion. (Also, I'd say "I am at university." -- and "I am in an armchair".)
I think when I thought of the university one, I thought of the general "I am enrolled in university". But yeah, being physically located on campus I would say "I am at university" too. Really should be what I put up there, sorry.
Esperanto has a general purpose preposition for when you don't know which more specific one to use.... it is "je."
In esposch's defence, Esperanto's spatial prepositions and constructions follow a very strictly logical patern and usage, so "laŭ" is VERY weird here. And given that Esperanto was consciously designed, Dr.Z could have borrowed a separate word.
It makes sense really. You go above or up according to the direction and way provided by the stairs! Though "per la ŝtuparo" does seem to make more sense to me.
It is more like "along the stairs". It is just a correct sentence, not a standard way of saying going upstars, but, I suppose, a way of teaching that "laŭ" can be used to indicate a route, as well, as, for example "according to someone".
In daily life, you'd probably just say, "Ni iru supren" or "Ni supreniru" (Let's go up) and leave off the part "along the stairs".
Thanks for the clarifications. Indeed, the sentences you give are shorter and more suitable for daily life situations.
So how would you say upstairs as an adjective? For example, "Use the upstairs bathroom."
You would usually just say just supre (up, over) as it usually does not matter if the person got there by stairs, by lift or any other way, just that they are on the the upper floor.
As others have pointed out, a more normal Esperanto translation for "Let's go upstairs" would be "Ni iru supren." I was given the longer Esperanto version, "Ni iru supren laŭ la ŝtuparo," and had to arrange given English words to translate it. I would have said something like "Let's go up this stairway" but there weren't enough words to insist on the method of reaching the upper level. The real point is: the idiomatic usage of the English word "upstairs" simply means "upper floor," without any insistence on a staircase. The problem here was caused by the English idiom, not any Esperanto difficulty. :-)