While listening to Conlangery recently I was impressed by one of the host’s suggestion to "try different things and see what works." It’s an anodyne, nearly cliché bit of advice, but it prompted me to wonder: how, exactly, does something in a constructed language "not work?" After all, you’re inventing a language. You get to make up the rules; whatever you invent works if you say it does. Doesn’t it?

Yet anyone who has been conlanging for more than a few months will recognize that this isn’t actually the case. I felt this intuitively, but it still had trouble articulating what exactly it meant for something to "not work" in an invented language. So I’ve compiled a list below of common conlang failure modes. These are things which frequently happen to conlang creators which cause their languages to go awry, and I think that almost all conlangers should be able to recognize many of the items on the list. More importantly, I’ve tried to articulate why each of the mishaps represents a failure, and how they detract from the artistic integrity of the conlang.

Relex: A relex is a language whose vocabulary exists in a close correspondence with the language creator’s native language. Relexes are a hallmark of new and naive conlangers, and they mostly represent a failure of imagination. Languages differ enormously in the structure of their vocabulary — why repeat what you already know?

Syntactic relex: A more sophisticated version of the relex, the syntactic relex mimics not the vocabulary but the grammar of the creator’s first language. This, likewise, is a failure of imagination, but it’s much subtler and is something that even sophisticated conlangers fall into periodically.

Excessive ambiguity: The language, as designed, is not really usable for communication because it presents too many opportunities for misunderstanding. No matter how creative or artistic a conlang is, it must still function (at least in theory) as a medium of communication. This is actually a hard error for most conlangers to fall into, since conlangers tend to hate unclarity, and the human language facility is remarkably tolerant of ambiguity.

Excessive specificity: The language, as designed, is not really usable for communication because it requires the user to encode too many different aspects of the utterance. There are myriad different things that languages can encode, but there is no language that encodes all of them. Many conlangers get overly excited about all of the different things that their language could mark, and try to throw in all of them. This results in a bulky, unwieldy morphology and syntax that resembles no real-world language.

Unlearnability: The language can’t be learned by ordinary humans, because it uses structures that aren’t natural for human minds. Occasionally, as with Fith, this is a deliberate design choice, but more often the language creators intended for the language to be human-speakable, but failed by choosing an unsuitable underlying model. Lojban seems to suffer from this flaw.

Incoherence: The parts of the language don’t fit together, and there are gaps or clashes where the mismatched parts meet. The language’s phonology might make mutually exclusive demands of its word-shapes, or the syntax might contain valency-changing operations which are superfluous in a non-configurational grammar. This usually indicates that the conlanger has included an interesting linguistic feature without understanding how to use it or considering its consequences for the rest of the grammar.

Artificiality: The language is unnatural in some way or another, and this unnaturalness marks the language as artificial. Any aspect of the language (phonology, morphology, syntax, vocabulary) can show these telltale signs of artifice. Occasionally this is a deliberate artificial choice, but more often this is a result of the conlanger attempting to create a naturalistic language and failing.

Aesthetic failure: The most difficult and subjective failure. Most conlangers begin their languages with a particular artistic purpose in mind, whether that goal is phonoaesthetic, morphosyntactic, or lexical. But sometimes the language fails to meet its creator’s goals. This failure is so idiosyncratic that almost nothing can be said about it in general, but anyone who has ever tried and failed at an artistic endeavor will understand what it is like.