I understand that several work has been done in regards to constructing languages that are both lexically and syntactically non ambiguous such as lojban. Is it possible to extend the work to eliminate ambiguous semantics?

  • What's in your opinion the difference between "lexically non-ambiguous" and "semantically non-ambiguous"?
    – Yellow Sky
    May 7, 2020 at 14:38
  • You’ll have to define semantic ambiguity first. When you say, “I have an apple in my hand”, does have refer time physically holding the apple, or is it about ownership? Does my hand mean the hand belongs to you, or that it’s part of your body? Does in mean that the apple is inside the hand or that the hand surrounds it? There’s nothing semantically ambiguous to us about any of these things, but there are languages that would distinguish these semantic roles lexicosyntactically – so are they cases of semantic ambiguity? May 7, 2020 at 15:03
  • Yes, of course it is. Programming language designers do it all the time. Of course, if you mean a language that is capable of talking about the phenomenological world (never mind human emotions and abstractions) it's a bit harder.
    – Colin Fine
    Sep 27, 2022 at 22:10
  • 1
    I told John Conway about Loglan/Lojban once, and he asked "Can you talk about cats in it?" When I said yes, he said he wasn't interested.
    – Colin Fine
    Sep 27, 2022 at 22:12

2 Answers 2


I would be extremely skeptical of any claims to having constructed such a language

To start with, (most?) words do not strictly define a set of referents, but some sort of fuzzy set, where examples further from the prototype(s) are only partially considered examples. An apple is indisputably a fruit, but lots of people will prevaricate when asked if a tomato is. If have any words defining fuzzy sets (rather than strict sets), you're doomed to failure from the start

Ok then, let's suppose we've somehow constructed a language where every word has a strict set of referents that it applies to. That is, each word is a predicate P(x) that returns true for an x that is an example, and false for an x that is not

You then go to teach it to another person, you see a dog and call it with the word P, you see a stone and call it not-P, you see several objects and teach the other person which are P and which are not-P. You tell them that cats, dogs, cows, kangaroos, rabbits, humans, and bats are all P, but stones, fish, bacteria, green, trees, lizards, heat, and birds are not-P.

When you are satisfied the learner has correctly mastered the language and is not making mistakes, you decide to take a holiday together and go on a whale-spotting trip where they happen to see a whale give birth to its calf. When the learner sees this, they call the whale P, but you disagree, calling it not-P

Wittgenstein would talk about this as part of a language game where we each have to guess how the other person is defining their terms. Each utterance you hear gives you information about how the other person is defining their terms, but, as good as your guesses may get, in a finite number of utterances, you will never be able to be 100% certain that the other person's definition of P matches yours. From those finite utterances, I can produce a heuristic to guess if a given referent is included in the definition, but out of the infinite possible referents I'm almost bound to make some mistakes, especially when it comes to referents neither speaker has encountered before (as opposed to one they have encountered before, but not discussed together), just take a look at the myriad different ways people have tried to describe the sensation caused by Szechuan peppercorns

So, even if you did manage to construct a language with unambiguous definition of every single word (something I doubt is possible), it would be impossible to guarantee you had taught it to someone such that they had internalised exactly the same definitions. If you can't be certain they've internalised the same definitions, you have to start considering the probability that a given referent is included in their definition and so you have to treat their speech as consisting of fuzzily defined terms and now we're back at lexical/semantic ambiguity


It is impossible to avoid ambiguity. First, let's define "ambiguity": the situation where a given linguistic form can refer to more than one state of affairs (or however you want to talk about what utterances are about). For example, "sharp scissors and knives" describes two distinct states, one referring to any knives, and also to scissors that are sharp. The second referent is the collection of sharp knives plus sharp scissors. There is ambiguity in English in "sharp scissors and knives". but not in "scissors and sharp knives", because the scope of an adjective in a structure "Adj N and N" can be the first N or the conjunction of Ns; there is no ambiguous scope in "N and Adj N". We can eliminate the ambiguity in various ways, such as having a specific marker for wide scope.

A sentence like "I cut the rope" might not seem to be ambiguous, but from a cross-linguistic perspective (in terms of how such a thing could be said in languages besides English) it is quite ambiguous. Did you cut the rope today, or yesterday (many languages require you to say how far in the past you did it)? Did you completely cut up the rope or just part-way? Did you intentionally cut the rope, or was it accidental. Why are you telling us that you cut the rope – is that a justification for something else? Or are you saying this because somebody asked what happened to the rope; is it a denial that you cut the tree (because it was the rope that you cut)? Languages have exuberant power to allow or require people to communicate information about circumstances, and languages differ in what information must be linguistically encoded.

If you don't want to reach the conclusion that all languages have some ambiguity, then you have to somehow redefine ambiguity. If I were in the business of redefining concepts, I would focus on the difference between ambiguity in scope, versus granularity of the conceptual sieve (sub-dividing "past" into "immediate past" vs "intermediate past" vs "remote past"). In virtually all syntactic theories, there is a formal gadget used to indicate that in "Who did he tell you to cook the beans for", "who" is the object of the preposition "for__", which sorts out these scope problems. All you have to do is mandate that this element be actually pronounced.

  • It's been proven that all written English sentences are multiply ambiguous (because writing doesn't represent all of the language signal). See Abney's famous paper
    – jlawler
    Sep 27, 2022 at 19:26
  • @jlawler But that's true of spoken English sentences too, right? And for many of the same reasons. And for some reasons which are not the same but are similar: whereas writing fails to distinguish homographs, speech fails to distinguish homophones.
    – Rosie F
    Sep 29, 2022 at 6:59

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