Fish and semantic theory

At this point in my French adventures, I’m reasonably capable of helping an American visitor navigate a French menu.  Quail, lamb, artichokes–I’ve got those under control.  The subtleties of the cheese plate–you’d be amazed.  Tajines versus couscous–I’m getting there.  Sausages–you want dry?  Spicy?  Halal?  Pork guts?

There’s still one part of the menu where I’m pretty hopeless, though.  It’s the fish section.  Here’s the thing: I don’t even know what the fish are in English.  Is flounder the flat one, or is that halibut?  Is haddock a dark fish, or a light fish?  I have no clue.  I know that tuna are really, really big and anchovies aren’t, but if you put me face to face with a monkfish and a sea bream, I’d be pretty lost.

This is curious.  Here’s the thing about lexical semantics–the meanings of words: theories of lexical semantics all assume that what we know about the meaning of a word is sufficient (a) to identify what it refers to, and (b) to distinguish what it refers to from what it doesn’t refer to.  Linguistics as we know it today begins with Saussure‘s observation that all meaning boils down to what you are not: I believe the quote is Dans la langue, il n’y a que des différences.  (“In language, there is nothing but differences.”)  We’re looked at a number of ways of representing word meanings in the past, including ontologies, prototypes, and necesssary and sufficient conditions.  The ability of a definition to distinguish between things is crucial to all of them.  The currently most popular approach to representing the meanings of words in the field of natural language processing, known as word embeddings, is based entirely on a spatial metaphor–similarities in meaning are closeness in meaning, differences in meaning are distances.  Nothing is defined in terms of any of its characteristics–it’s all about which other words a word is more, or less, different from.  All of these approaches to semantics require not just that you be able to define what a thing is, but also differentiate it from the things that it isn’t.

So, how do you fit fish into this?  They’re just one example of a phenomenon that is not uncommon.  It doesn’t have a name, that I know of, but I’ll bet that you can give your own examples of it.  Here are some from my own experience:

I know what everything in columns A, B, and C have in common.  Column A is precious stones.  Column B is trees.  Column C is colors.  But, which stones, trees, colors?  I haven’t a clue.  I know how they’re similar, very broadly–they’re all stones/trees/colors.  But, I couldn’t tell which was which if my life depended on it.

So: how do you explain this phenomenon where I know what kinds of things they are, but I don’t know specifically what they are?  I know a similarity–it’s the difference that I don’t know.  How you fit that into a theory of meaning that relies crucially on being able to differentiate between things, I have no clue.  And, it’s not like this is rare, either: I’ll bet that if pushed, you could come up with a list of things that you know are geographic features, without actually being able to define them (hill, hillock, dale, dell, valley, hollow, swale); same for furniture (settee, chaise lounge, tuffet, ottoman); fish, perhaps?  A request: if I’m the only freak in the world who knows categories of words that he can’t tell apart, feel free to leave me in peace.  But, if there are categories of words like that that you don’t know how to define the members of, either, could you let me know that I’m not alone in my weirdness by giving me examples?  And, if you’re a linguist, and you know the name of this phenomenon: please enlighten me…

• le thon: tuna
• la truite: trout
• la daurade: sea bream