Tuesday, September 8, 2015

An attempted taxonomy of everything

There is some sense in which the peach I’m eating is a different kind of thing than the thoughts I’m thinking, and there is some sense in which the last book I held in my hands is a different kind of thing than the story it contained. I suspect you know what I mean, but let’s not stop there. Is there some systematic way to organize all of the different “kinds of things” I can think of?

People with different worldviews might categorize the concepts they know of in different ways. But we mostly share the same basic picture: there are actions and there are things, and both actions and things have properties.  This common perspective shouldn’t be surprising, since these mental categories are built into our languages. In English, at least, there are four main types of words: verbs (for actions), nouns (for things), adverbs (for properties of actions), and adjectives (for properties of things). However, my goal is not to write a taxonomy of the English language; rather, I want to taxonomize all the concepts that live in my head. The English language has such an intimate relationship with the concepts in my head that its structure will surely shape the way I categorize them, but there is not a one-to-one map between words I know and concepts that live in my head. Some examples: I don’t have independent mental notions of “shiny” and “shininess”; “to” doesn’t really mean anything at all to me until it’s used in a phrase, like “to the park”; some concepts, like the one referred to by “dialectical materialism,” take many words to express.

Before I start, I’d like to give a big disclaimer.  Although there are probably linguists who have worked out much better versions of what I’m trying to do here, I decided it would be fun to try this on my own. It has been fun, but it has also been super confusing and difficult, and I’ve made decisions I’m not sure about. So this taxonomy can likely be improved in at least three ways. First, I might be missing some categories entirely—are there concepts you know of which don’t fit into my framework at all? Second, there might be ways to organize the concepts that I have included in a way which is just objectively more clear. Third, it may be that there is no objectively “best” taxonomy; you and I might just have different perceptions of which concepts are similar and which are dissimilar, in which case there may be better taxonomies for you but not for me. Feel free to comment on and criticize the way I've categorized things! I'd love to see how someone else might do this differently.

The taxonomy
First, I’ll take the basic picture we have from the English language: there are actions and things, and both actions and things have properties.  I’m going to give the sub-taxonomies of properties, actions, and things, in that order—one of increasing depth and interest.

Some properties describe actions and some describe things. Some action properties—like those expressed by “quickly” or “blindly”—are those the English language calls adverbs. Prepositional phrases (e.g. “to the park”) can also be used to express properties of actions. Similarly, properties of things are either expressed by adjectives or by prepositional phrases (note that certain prepositional phrases that can apply to some actions, like “to the park,” can not apply to things).

I keep writing things along the lines of “those concepts expressed by words like” as a reminder that this is a taxonomy of concepts in my head and not one of words. I stop including these reminders later in the post, for the sake of brevity.

I think actions are best categorized along three dimensions, rather than split into groups which are each split into subgroups, etc.

Dimension 1: degree of activity
Actions vary in how much engagement or focus-in-the-moment they require from the doer.  For example throwing is a little more active than breathing, which is a little more active than believing, which is a little more active than existing. There is a whole continuum along which actions lie. To be clear, the action that a word like “breathing” expresses can be done at many different levels of activity (e.g. if meditating and focusing on one’s breathing); in the previous sentence, I was referring to the level of activity of the actions those words most often express.

Dimension 2: internal-external
This dimension is a binary one. Although—at least from my physicalist perspective—any mental action corresponds to a physical event which could in principle be observed externally, we tend to think of actions like pondering as taking place within my head while some actions like surfing take place outside of it. The clearest way I can say this is: internal actions are those the actor could not do were it a philosophical zombie version of itself, whereas external actions could be done just as well by philosophical zombie equivalents. The same physical process can be thought of as either external or internal; it depends upon whether we focus on what happens physically or on what the physical process was like to experience.

Dimension 3: tense
There are a handful of different tenses that verbs can come in, and these correspond to different concepts of what is being done. I mean something different when I say that “I ate a carrot” than when I say that “I was eating a carrot” or  “I would eat a carrot,” etc.

Some examples and an two important difficulties
When I use the word “spat,” I’m referring to a concept with a high degree of activity which is external in the simple past tense. “Would believe” is low activity, internal, and subjunctive. “Am considering” is medium-active, internal, and present tense.

But how would we categorize the concept I’m referring to when I say, “I looked around the room”? Is the action here internal or external? Both, I think; “I looked around the room” is a sentence which expresses two different ideas at the same time—first the external action of moving my eyes around and second the internal action of systematically perceiving my surroundings. This idea—that one sentence (or even one word!)—can express multiple concepts at the same time is an important one which will come up again.

A second challenge: It’s temping to say that the tense expressed by sentences like “I went running” is just simple past tense. However, some would say that the concept expressed by the sentence is not that the event John-goes-running actually occurred but rather that I currently remember having gone running. My response here is that, again, the sentence can express multiple meanings at once. I think most speakers would intend to express that they remember going running and that the event did actually happen. How strongly their statement intends to express each of these components depends on who they are (and probably how much Descartes they read).

I’ll divide all the things I can think of into five categories and further subdivide some of these groups.

Action-derived things
Given any verb, we can construct a noun (a gerund) by adding “ing.” We can also sometimes add other endings too; for example, “to erode” can become “eroding” or “erosion.”  I’m not sure whether my concepts of thing-ified actions are in general distinct from their source actions; the thing that is “running” seems no different in my head from the action expressed by “running,” but the idea of a “diversion” does at least seem to have some connotations that aren’t captured well by “divert.” Anyhow, I’ve decided to tentatively include this category.
The internal structure of actions-derived things can be carried over from the words they are sourced from (just leave out the tense dimension).

Property-derived things
As with verbs, we can convert adverbs and adjectives into nouns. “Wise” becomes “wisdom” and “chaotic” becomes “chaos.” Again, I’m unsure whether I understand thing-ified properties in ways distinct from their source properties. “Shiny” feels the same as “shininess” but “wisdom” feels like it may capture a little more than does “wise.” I’ve decided to tentatively include this category, too.
We can give a little bit of structure to property-derived things by thinking about what the properties were properties of. Some property-derived things, like those expressed by “chaos” or “synchronization,” describe a system—we will call these states. Others, like those expressed by “redness” or “wit,” describe a singular entity—we will call these qualities.

External things
Having dispensed with things that are derivative of actions and properties, we’re left with things that feel more thing-like. Of these, some (like emotions) depend on the mind in order to exist, and some do not. We will use the category external things to describe things that exist with or without sentient beings. I'll break external things into two subgroups.

Physical objects
Ah, finally something we understand! Physical objects are all the things made up of fundamental particles. They’re the stuff we can touch, the stuff that’s too small for us to touch, and the rest of the basic entities to which physics applies. Most physical objects we can either think of as conglomerates—groups of individual parts—or as singular wholes.

Facts and Rules
There are some facts about how the world is and rules about how it works. These are the what science (and social science, and all sorts of other endeavors) attempt to learn about and describe. Some of these facts and rules are absolutes, like that the sun is larger than the earth and that (to our knowledge) the laws of physics work however it is that they work. Others—like laws of human behavior—are more like rules of thumb which apply in some probabilistic or approximate sense.

It’s important to distinguish the way things are from the way we think they are: the rule that protons and electrons attract is a different thing from the claim, written in some textbook, that protons and electrons attract. The latter is science and the former is the actual phenomenon that science seeks to describe. The former is how things work, whether or not they are being studied (at least this is the view most people take most of the time), whereas the latter is something constructed by humans.

Mental things
This is the category for things that—while they also have physical incarnations in our mind—we think of existing within our minds. We can break them into three sub-sub-categories. First there are things that we just experience raw: sense-data, moods, and emotions. Then there are mental objects related to representing the world: worldviews (assignments of structure onto our experiences) and beliefs attached to notions of certainty or probability.  Thirdly, there are the things which we understand to help us determine our actions: these are desires and values. Intuitions are a final kind of mental object, which could either be considered part of our raw experience or part of our system of beliefs.

Mind-dependent, individual-independent things
What kind of thing is the story of Little Red Riding Hood? What kind of thing is the idea of a university? What kind of thing is the claim that markets seldom exist in equilibrium? These things are clearly not external the way objects are—I can’t touch them, for sure—and they are also aren’t human-independent facts about the world. But they are more universal than what we’ve called “mental things”; whereas my belief it’s Friday isn’t the same thing as your belief that it’s Friday (simply because it’s your belief), we think of the story of Little Red Riding Hood as being the same story whether it’s in my head or yours (so long as we know the same version). That is to say, the substrate in which it exists is not relevant to its identity. And yet, if there is no mind thinking about some story, or, further, if there is no mind that will ever (or even could ever) think about some story, does the story still exist? I don’t really think so. There may be physical objects (books) capable of causing the story to exist in a mind, but in the absence of minds to hold the stories, I think it makes more sense to say they don’t exist.

Anyhow, we now have a final category of things: those whose existence requires instantiation (or at least the future possibility of it) in some sentient mind, but whose identities are constant across the minds in which they are conceived (assuming they are fully understood). We’ll break these into three subgroups.

There are some things whose functions are to gesture toward other things. For instance, the symbol “<” is generally thought of not in terms of its shape or color, but in terms of the mathematical concept we understand it to represent. And yet we have a notion of the symbol “<” itself, distinct from the concept it points to. We’ll call these things—those whose function is just to point to other things—“pointers,” and we’ll divide them into two subcategories.

The first subcategory of pointers is those that are part of a formal language. We include in this category: letters, which point to particular sounds; letter-composed words (or those formed from something else, e.g. Chinese characters), which point to particular things, actions, properties, etc.; and word-composed phrases or sentences, which point to more complicated concepts or strings of concepts. It’s worth noting that mathematics is a formal language, too. Math has symbols and rules about what symbols make sense in which combinations, and strings of mathematical symbols point to ideas which we (usually) understand as something above and beyond the symbols themselves.

That leaves the second subcategory of pointers to contain the ones that are not incorporated into any formal language. For instance, (at least in Western literature) fires tend to symbolize passion and mirrors tend to suggest some kind of self-reflection. However, I don’t know of any formal language that, say, has fire-shaped and mirror-shaped characters for passion and self-reflection, respectively.

Compared to those in formal language, pointers outside of formal language tend to be things that we can also conceive outside of their roles as pointers; fires and mirrors are things in of themselves and also have had pointer-meanings attached to them, whereas “<” has little meaning outside of the concept it represents. This brings us back to the idea that a single linguistic word can have multiple meanings at the same time. If I point at some wood burning and use the word “fire,” I am simultaneously referring both to fire the physical object and to fire the non-formal-language pointer.

Truth-related / proposition-based constructs
In logic, a proposition is the kind of statement to which one can assign a truth-value (true or false or some degree of uncertainty). In English, declarative sentences (as compared with, say, questions or exclamations) can be thought of as expressing propositions, because we can imagine how they might be true or false. While one can string together concepts we’ve already categorized in order to form propositional statements, we wouldn’t yet be able to be explicit about whether the sentences are intended to express some truth-related content; the sentence “I ate dinner” might just intend to express the idea of me having eaten dinner rather than the claim that I did, in fact, do it. This category is my attempt to capture the notion that statements can have some semantic truth-value rather than just expressing the idea of things.

We can subcategorize a bit: First we just have propositions, which are statements of the proper form for us to consider attaching truth-values to them. Then we have claims, which are propositions with truth-values attached (e.g. “the sun will almost definitely rise tomorrow,” or “it’s possible that I’ll go blind”). Things like hypotheses, conjectures, and theorems fit under the umbrella of claims. Finally, we are familiar with groupings of various claims (with varying degrees of certainty); we call these groupings things like theories or frameworks.

This category bears some similarity to the subcategory of external things that we called “facts and rules”—both are about instances of objective truth. These categories are, however, different in an important way. Propositions, claims, theories, etc. are statements about the way things are, whereas facts and rules just are the way things are. Members of the former category attempt to describe members of the later.

(Non-truth-related) Notions
In the last section I brought up that sometimes we just think about “the idea of things,” without considering any claims. This subcategory contains notionsthose mind-dependent, individual-independent things that we just consider, not as things that might be true or false but merely as thoughts. This allows us to capture things like the idea of a university and things we express in phrases like “that I went to the store.”

This subcategory also captures stories; the story of Little Red Riding Hood doesn’t make any particular claims about the world (it’s not saying that the story every happened), but rather just gives us a series of hypothetical events to consider. What about stories like the one in the Bible, which sometimes are understood as telling us that particular things actually happened? I’d say—as I seem to be saying about all the confusing concepts—that we conceive of the Bible as doing two different things at once. It is both a story (something that just encourages us to consider some hypothetical series of events) and a series of claims about some events in the past. Some would say that it’s a third thing too: a series of claims about abstract concepts that one has to read the Bible the informal language of symbols in order to understand. And of course, “the Bible” also refers to a group of physical objects that fit some description.

I’d like to elaborate on an important subgroup of notions, namely the kind involved in plural nouns. When I say “dogs tend to smell bad,” the concept I’m expressing with “dogs” is not a list of all dogs, since that’s far too cumbersome for my mind to handle. Rather, “dogs” has more to do with “the idea of dogs”—it means something more like “things which have certain properties which are shared by each thing I’ve been told is a dog.”  To say that more generally: I conceive of plural nouns as functions from things to truth values; each plural-function takes in some thing, evaluates whether it is, say, a dog, and then returns “yes” or “no” (or sometimes something in between). Most of these plural-functions seem to work internally by evaluating whether some particular thing satisfies most or all of a list of properties which I use to describe the group. Sometimes, like in the case of “members of the Beatles,” my plural-function works more simply, by just comparing the thing in question to the things written on some list (“Is it John Lennon? Is it Paul McCartney…”).

I'll give two different kinds of summaries--one in bullet points and the other in a picture.

Bullet-point summary
  • Properties
    • Of Actions
      • “Adverbs”
      • Prepositional phrases
    • Of Things
      • “Adjectives”
      • Prepositional phrases
  • Actions
    • Dimension 1: degree of activity (or awareness of action while doing it) (continuous)
    • Dimension 2: internal-or-external (binary) (“is it something I could do if I were a philosophical zombie?”)
    • Dimension 3: tense (finite)
  • Things
    • Action-sourced things (if they’re really distinct from actions)
      • Organized with internal-or-external binary and degree of activity
    • Property-sourced things (if they’re really distinct from properties)
      • System-describing (states)
      • Individual-describing (qualities)
    • Physical things
      • Physical objects
      • Facts and rules (about what there is and how things work)
    • Mental things
      • Raw-experienced things
        • Sense-data
        • Moods
        • Emotions
      • Representations
        • Worldviews
        • Beliefs and knowledge, notions of likelihood or probability
      • Internal choice-determinants
        • Desires
        • Values
    • Mind-dependent, individual-independent things
      • Pointers
        • Formal language
          •  Letter-symbols
          • Words (combinations of letter-symbols)
          • Combinations of words
        • Informal symbols
      • Truth-related / proposition-based constructs
        • Propositions
        • Claims (propositions with truth values assigned)
          • Hypotheses
          • Conjectures
          • Theorems, etc.
        • Groupings of the above types
          • Theories
          • Frameworks
      • (Non-truth-related) Notions (just the idea of things)
        • Stories (or the story-like component of more claim-based accounts)
        • Plurals (functions that take in things and say whether they fit in some group)
        • Others

Visual summary

Thank you
To Margaret, for talking about this and pointing out all kinds of conceptual difficulties.

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