Language off in the weeds

While out walking, I paused to look at a stand of cattails (genus Typha) growing in a streambed leading to a pond.  "That's a pretty ..." I thought to myself, but what would be the word for the area they were growing in? Marsh? Wetland? Swamp? Bog? Something else?

I've long been fascinated by this sort of distinction.  If you don't have much occasion to use them, those words may seem interchangeable, but they're not.  Technically

• A wetland is just what it says ... any kind of land area that's wet most or all of the time
• A marsh is a wetland with herbaceous plants (ones without woody stems) but not trees
• A bog is a marsh that accumulates peat
• A swamp is a forested wetland, that is, it does have trees

Wikimedia also has a nice illustration of swamps, marshes and other types of land.  By that reckoning, I was looking at a marsh, which was also the word that came to mind at the time.

This sort of definition by properties is everywhere, especially in dictionaries, encyclopedias and other reference works.  Here, the properties are:

• Is it land, as opposed to a body of water?
• Is it wet most or all of the time?
• Does it have trees?
• Does it accumulate peat?

The first two are true for all of the words above.  For the last two, there are three possibilities: yes, no and don't care/not specified.  That makes nine possibilities in all

Trees?	Peat?	Word
Yes	Yes	peat swamp
Yes	No	?
Yes	Don't care	swamp
No	Yes	bog/peat bog
No	No	?
No	Don't care	marsh
Don't care	Yes	peatland
Don't care	No	?
Don't care	Don't care	wetland

As far as I know, there's no common word for the various types of wetland if they specifically don't accumulate peat.  You could always say "peatless swamp" and so forth, but it doesn't look like anyone says this much.  Probably people don't spend that much time looking for swamps with no peat.

Leaving aside the empty spaces, the table above gives a nice, neat picture of the various kinds of wetland and what to call them.  As usual, this nice picture is deceptive.

• I took the definitions from Wikipedia, which aims to be a reference work.  It's exactly the kind of place where you'd expect to see this kind of definition by properties
• The Wikipedia articles are about the wetlands themselves, not about language.  They may or may not touch on how people use the various words in practice or whether that lines up with the nice, technical definitions
• The way the table is set up suggests that a peatland is a particular kind of wetland, but that's not quite true.  A peatland is land, wet or not, where you can find peat.  Permafrost and tundra can be peatland and often are, but they're not wetlands.  Similarly, a moor is generally grassy open land that might be boggy, if it's low-lying, but can also be hilly and dry.  Both peatlands and moors can be wetlands, but they aren't necessarily
• Even if you take the definitions above at face value, if you have a lake in the middle of some woodlands with a swampy area and a marshy area in between the lake and the woods, there's no sharp line where the woods become swamp, or the swamp becomes marsh, or the marsh becomes lake.

The Wikipedia article for Fen sums this up nicely:

Rigidly defining types of wetlands, including fens, is difficult for a number of reasons. First, wetlands are diverse and varied ecosystems that are not easily categorized according to inflexible definitions. They are often described as a transition between terrestrial and aquatic ecosystems with characteristics of both. This makes it difficult to delineate the exact extent of a wetland. Second, terms used to describe wetland types vary greatly by region. The term bayou, for example, describes a type of wetland, but its use is generally limited to the southern United States. Third, different languages use different terms to describe types of wetlands. For instance, in Russian, there is no equivalent word for the term swamp as it is typically used in North America. The result is a large number of wetland classification systems that each define wetlands and wetland types in their own way. However, many classification systems include four broad categories that most wetlands fall into: marsh, swamp, bog, and fen.

A fen here means "a type of peat-accumulating wetland fed by mineral-rich ground or surface water."  It's that water that seems to make the difference between a bog and a fen: "Typically, this [water] input results in higher mineral concentrations and a more basic pH than found in bogs." (bogs tend to be more acidic).  We could try to account for this in the table above by adding an Acidic? (or Basic?) column, but then we'd have 27 rows with a bunch of question marks in the blank spaces.

In that same paragraph, the article says "Bogs and fens, both peat-forming ecosystems, are also known as mires."  If you buy that definition, it might fit better than peatland in the "trees: don't care, peat: yes" row.

This is all part of a more general pattern: Definitions by properties are a good way to do technical definitions, but people, including technical people when they're not talking about work, don't really care about technical definitions.  For most purposes, radial categories do a better job of describing how people actually use words.  More on that in this post.

All of this is leaving out an important property of bogs and mires: you can get bogged down in a bog and mired in a mire.  Most of these words are old enough that the origins are hard to trace, but bog likely comes from a word for "soft", which more than hints at this (mire is likely related to moss).

This suggests that what we call something depends at least in part on how we experience it.  The interesting part is that defining properties like wetness, grassiness, softness and the presence of peat are also based on experience, which makes untangling the role of experience a bit tricky.

Just because we can distinguish meanings doesn't mean those distinctions are useful, but I'd say they are useful here, and in most cases where we use different words for similar things.  The distinctions are useful because we can draw larger conclusions from them.  For example:

• It's easier to see what's on the other side of a marsh, since there are no trees in the way
• A marsh will be sunnier than a swamp
• There will be different kinds of animals in a swamp than a marsh
• You can get peat from a bog.  Even today, peat is still a useful material, so it's not surprising that it's played a role in how we've used words for places that may or may not have it.
• And it's also not surprising that people talk about peat bogs and peat swamps but generally don't specifically call out bogs and swamps without it.

Even the more general term wetland is drawing a useful distinction.  A wetland is, well, wet.  There's a good chance you could get stuck in the mud in a wetland, or even drown, not something that would happen in a desert unless there had been a downpour recently (which does happen, of course).

Let's take a completely different example: Victorian cutlery.  Upper middle-class Victorian society cared quite a bit about which fork or spoon to use when.  Much of this, of course, is about marking membership in the in-group.  If you were raised in that sort of society, you would Just Know which fork was for dinner and which for salad.  If you didn't know that, you obviously weren't raised that way and it was instantly clear that there could be any number of other things that you wouldn't know to do, or not do (If you ever have to bluff your way through, work from the outside in -- the salad fork will be on the outside since salad is served first -- and don't worry, something else will probably give you away anyway).

However, there are still useful distinctions being made, and they're right there in the names.  A salad fork is a bit smaller and better suited for picking up small pieces of lettuce and such.  A dinner fork is bigger, and better for, say, holding something still while you slice it with a knife.  A soup spoon is bigger than a teaspoon so it doesn't take forever to finish your soup, a dinner knife is sharper than a butter knife, a butter knife works better for spreading butter, and so forth.

It's no different for the impressive array of specialized utensils that one might have encountered at the time (and can still find, in many cases).  A grapefruit spoon has a sharper point with a serrated edge so you can dig out pieces of grapefruit.  A honey dipper holds more honey than a plain spoon and honey flows off it more steadily (unless you have a particularly steady spoon hand) and so on.  I have an avocado slicer with a grabber that makes it much easier to get the pit out.  It's very clear (at least once you've used it) that it's an avocado slicer and not well suited for much else.  You can do perfectly well without such things, but they can also be nice to have.  

Consider one more example: The fondue fork, which has a very long, thin stem and two prongs with barbs on them.  You could call it, say, a barb-pronged longfork, and that would be nice and descriptive.  If someone asked you for a barb-pronged longfork and you had to fetch it from a drawer of unfamiliar utensils, you'd have a pretty good chance of finding it.  If someone asked for a "fondue fork" and you didn't know what that was, you'd pretty much be stuck.  The same is true for grapefruit spoons, dinner knives and so forth.  All language use depends on shared context and assumptions about it.

I think there's something general going on here, that how we experience and interact with things isn't just a factor in how we name them, but central to it.  Even abstract properties like softness or dryness are rooted in experience.  Fens and bogs have different soil characteristics, but the names are much older than the chemical theory behind pH levels.

We call it a fondue fork because it's used for putting bits of food in a fondue pot (and, just as importantly, for getting them back out).  A fondue fork has certain qualities, like the long stem and the barbs, that make it well-suited for that task, but they're not directly involved in how we name it.

Words like fen and bog are distinct because fens and bogs support distinct kinds of plant and animal life, moving through a fen is different from moving through a bog, and so forth.  A difference in pH level is a cause of this difference, but that's incidental.  There are almost certainly areas that are called fens that have bog-like pH levels or vice versa.  You could insist that such a fen (or bog) is incorrectly named, but why?

Properties do play a role in how we name things.  Swamps have trees.  Marshes don't.  A knife has a sharp edge.  A fork is split into two or more tines.  A spoon can hold a small amount of liquid.  What we don't have, though, is some definitive list of properties of things, so that someone presented with a teaspoon could definitively say: "This thing is an eating utensil.  It can hold a small amount of liquid.  That amount is less than the limit that separates teaspoons from soup spoons.  Therefore, it's a teaspoon."

In many contexts, it may look like there is such a list of properties.  With marsh and swamp, we can clearly distinguish based on a property -- trees or no trees.  Sometimes, as with red-winged blackbird or needle-nose pliers, but not for marsh and swamp, we use properties directly to build names for things.

But there are thousands of possible properties for things -- sizes, shapes, colors, material properties, temperature, where they are found, who makes them, and on and on.  Of the beyond-astronomically many possible combinations, only a tiny few describe real objects with real names.

At the very least, there has to be some way of narrowing down what properties might even possibly apply to some class of objects.  Stars are classified by properties like mass (huge) and temperature (very hot by human standards), but we don't distinguish, say, a fugue from a sonata based on whether the temperature is over 30,000 Kelvin.

It's not impossible, at least in principle, to create a decision tree or similar structure for handling this.  You could start with dividing things into material objects, like stars, and immaterial ones, like sonatas and fugues.  Within each branch of the tree, only some of the possible properties of things would apply.  After some number of branches, you should reach a point where only a few possible properties apply.  If you're categorizing wetlands, you know that the temperature classifications for stars don't apply, and neither do the various properties used to classify musical forms, but properties like "produces peat" and "has trees" do apply.

In practice, though, even carefully constructed classification systems based on properties, like the Hornbostel-Sachs system for musical instruments discussed in this post, can only go so far.  Property-based systems of classification tend to emphasize particular aspects of the things being categorized, such as (in the case of Hornbostel-Sachs) how they are built and how sound is produced from them.  This often lines up reasonably well with how we use words, but I don't think properties are fundamental.

Rather, how we experience things is fundamental, or at least closer to whatever is fundamental.  Properties describe particular aspects of how we experience something, so it's not surprising that they're useful, but neither should it be surprising that they're not the whole story.