Organize human activities into 10 mutually exclusive and collectively exhaustive categories / 人間の活動をMECEで10個に分けて整理する
This is an inquiry into whether human activity can actually be classified into 10 categories using MECE principles. The text is primarily written in Japanese. The English version is machine translated.
When we discuss our thoughts and actions, we often debate or worry about things like: “Really intelligent people are like this, but you’re stupid,” “Which is better, science or humanities, or does it make sense to separate them?” “Isn’t correctness suffocating?” “What is freedom?” Often, due to inadequate organization, troubles arise or we fail to act ideally. I believe the reason for this confusion is that different topics are mixed together, which is what I want to explore in this text.
When humans engage in activities, there is always some axis and some result. For example, mathematics obtains theorems and formulas using calculation as its axis. When shopping, we decide what we want to buy, search for those items in a store, and purchase them. In other words, we use calculation or what we want to buy as the axis and obtain theorems, formulas, or purchased items as results. However, isn’t the relationship between axis and result different in mathematics and shopping? My hypothesis is that the confusion we described above results from confusion regarding the interpretation of axis and result.
I have developed a method to divide human activity into just 10 types with no omissions or overlaps. This is what we call MECE, and the strength of this method is that human activities always fit into exactly one category when interpreted.
Moreover, the classification described in this text can be applied beyond humans. It can be applied to other animals, and to AI activities, which are currently a hot topic as of 2026. Even if aliens suddenly appeared, we could respond appropriately. Including this level of abstraction, it is a strong theory.
What is described in this text is merely classification. To repeat, it is one clue that can be used to settle discussions and resolve worries. It does not rank things as superior or inferior, nor does it directly relate to decision-making. It certainly isn’t about fixed ideas that rashly judge things based on bias and prejudice. When individuals or groups think about something, it will be useful in clarifying the axis and results. Once the axis and results are clear, it should become clear what you need to study to gain broad and deep insight into discussions and worries, and I will provide guidance on that in this text. I hope this theory will help us acquire true education and develop the ability to think in ways that can withstand changes in the times.
First, let me introduce the “characters” in human activity. Let me start with concrete examples. When studying mathematics, we first learn basic theorems and formulas, then make some sort of guess at the answer to a given problem. Then we actually calculate to verify whether our guess was correct. Shopping is similar. First, we have something we want to buy and assume we can purchase it. We talk to store staff and pay money to obtain goods or services. What about science? We observe actual natural phenomena and develop theories or explanations that can properly explain them through experimentation and observation. Mathematics study, shopping, and scientific explanation are done by humans. In the future, robots like Astro Boy and Doraemon might do the same things.
In any case, humans recognize something or think of it in their minds, and then use their minds and bodies. The trial-and-error process of using one’s mind and body is called “processing.” What remains unchanged during processing is called “input/output,” and the main body doing the processing is called the “agent.” In the examples above, “mathematical guesses,” “what we want to buy,” and “natural phenomena” are “input/output.” “Calculation,” “how to shop,” and “experimentation, observation, theory-building, and explanation” are “processing.” “Humans,” “Astro Boy,” and “Doraemon” are “agents.”
The “characters” are of three types: “agent,” “input/output,” and “processing.” By dividing this “input/output” and “processing” into 3 types each, and designating one as the “axis” and the other as “results,” we can divide them into 18 (where $3^2 \times 2 = 18$) types in a MECE manner. By excluding ineffective ones and grouping some into the same classification, we reduce this to 10 types, which I will discuss later.
Let me summarize “agent,” “input/output,” and “processing” in a table and end this section. To gain deeper understanding, you should think of many concrete examples. For instance, a “programmer” is an “agent,” “interface” is “input/output,” and “implementation” is “processing.” There should be many other examples, so try to find them.
| Term | Explanation | Example |
|---|---|---|
| Processing | Some form of trial and error | Calculation, how to shop, experimentation, observation, theory-building, explanation, implementation |
| Input/Output | What remains unchanged during “processing” | Mathematical guesses, what we want to buy, natural phenomena, interface |
| Agent | The main body doing the “processing” | Humans, Astro Boy, Doraemon, programmers |
In the previous section, I mentioned dividing “input/output” and “processing” into 3 types each. This section discusses how to divide these three types. Please read carefully, noting that this threefold division is a MECE with no omissions or overlaps.
When dividing, we focus on whether the agent can change something, and if the agent can change something, whether it’s just one thing or more than one.
Let’s first think about input/output. Mathematical guesses and what we want to buy are matters of personal freedom, so we can change them freely. Moreover, since it’s a personal thought, there’s only one thing being changed. What about natural phenomena? Even if we pray or stage social movements, the laws of motion don’t change, so there are 0 things we can change. What about interface? For those unfamiliar with programming, an interface is like the specification of an app’s screen. It refers to the part users touch when using software or its specifications (properties). When considering an interface, we should work with users, not just developers. If developing commercially, we need to coordinate with management and sales in addition to users. These stakeholders can also be changed depending on how we communicate. In other words, when we consider ourselves and multiple other people, there are two or more things we can change.
The same argument applies to processing. As long as the formulas or theorems1 are correct, calculation results don’t depend on who does them. If they differed from person to person, mathematics would be broken. As long as the foundation is the same, there are 0 things humans can change regarding truth or falsehood2. Regarding how to shop, it involves interaction with a store clerk, so two or more things can be changed. Scientific experimentation, observation, theory-building, and explanation can be improved to match natural phenomena. If done alone, there’s 1 thing that can be changed. If done with people with different hypotheses or from various backgrounds, there are 2 or more things that can be changed. Software implementation, considered at the development team level, has 1 modifiable thing (one team). Thus, processing also has modifiable things like input/output, and we can count how many.
When considering the above “input/output” and “processing,” we call those with 0 modifiable things “objects,” those with 1 modifiable thing “individuals,” and those with 2 or more “society.” Since the number of things is a non-negative integer, we can classify completely without omission or overlap with 0, 1, or 2+. The collective term for “objects,” “individuals,” and “society” is “modifiable entities.”
Note that “modifiable entities” are not fixed by a single belief. These classifications are merely for organizing discussions and worries, and which category—”objects,” “individuals,” or “society”—something falls into depends on context. The same thing might be classified differently depending on the kind of discussion or worry. For example, mathematical proofs are “objects” when we focus only on truth value, but might be “individuals” or “society” when we focus on the beauty or elegance of the proof. Similarly, what we want to buy might cause internal conflict if we must choose one from several due to budget constraints. If there are two or more conflicting desires within one person, it might be “society” rather than “individual.” Even a program interface might be “individual” rather than “society” if we view developers, users, management, and sales as a unified community. In this way, what falls under “objects,” “individuals,” or “society” changes with context. However, the key point is that regardless of context changes, something always falls under one of these three types.
“Modifiable entities” is a very important concept for thinking about the axis and results of human activity. Let me end this section by making a table and reviewing it. To repeat, be aware that concrete examples are context-dependent.
| Term | Explanation | Example |
|---|---|---|
| Objects | “Input/output” or “processing” with 0 modifiable things | Natural phenomena, calculation |
| Individuals | “Input/output” or “processing” with 1 modifiable thing | Mathematical guesses, what we want to buy, solo experimentation and explanation, implementation, beautiful proof |
| Society | “Input/output” or “processing” with 2 or more modifiable things | How to shop, interface, group experimentation and explanation, conflicting desires |
From here, let’s discuss axis and results. Humans judge something as correct and act on it, then develop activities based on that. Let’s see this flow through concrete examples, relating to examples of “input/output” and “processing.”
When studying mathematics, we make some guess at the answer to the problem. By actually calculating, we discover whether our guess was correct or wrong, and we then change our mathematical knowledge accordingly. The same applies to shopping. First, we have something we want to buy and assume we can purchase it. If we couldn’t purchase it, the problem might have been in our communication with the store clerk. It’s possible we went to the wrong shop or didn’t have enough money. In any case, we reflect on how to shop successfully next time. What about scientific experiments? We develop explanations or theories that match natural phenomena. If experimentation or observation reveals problems, we change the explanations or theories. Software developers also change their implementation if it doesn’t match the interface.
In this way, after “processing” ends, we compare “input/output” and “processing,” use one as an axis, and appropriately change the other to achieve results. Results might be better expressed as “growth” in some cases. The quality of the side that becomes the axis for judgment and remains fixed is called “validity,” while the quality of the side that becomes results and might be changed is called “development.” Mathematics assigns “validity” to the “processing” of “calculation” and “development” to the input/output of “guesses.” Shopping, science, and software development assign “validity” to the input/output of “what we want to buy,” “natural phenomena,” and “interface,” respectively, and “development” to the processing of “how to shop,” “experimentation, observation, explanation, and theory,” and “implementation.”
We must be careful not to confuse “input/output” and “validity.” “Input/output” remains unchanged only “during processing”; it can change after processing. Conversely, “validity” must not be changed when comparing “input/output” and “processing” after processing. For example, a mathematical guess doesn’t change during calculation, but if it’s wrong after calculation, we can change it. The same applies to “processing” and “development.” “Processing” is inherently trial-and-error, and whether to change the criteria for this trial-and-error after processing is a separate issue called “development.” In the previous example, we do trial-and-error in creating a mathematical proof, but that doesn’t mean the truth value of a proposition can be freely changed.
Like “modifiable entities,” the assignment of “validity” and “development” is also context-dependent. For example, when focusing only on the truth value of a mathematical proposition, the “processing” of “proof” has “validity” and the input/output of “guess” has “development.” But when focusing on the beauty of mathematical proof, the “processing” of “proof” has “development” and the standards of mathematical beauty have “validity.” In either case, we assign “validity” to either “input/output” or “processing” and “development” to the other. Which we assign to which depends on context, but there are only two ways to assign them.
Finally, let me make a table summarizing “development” and “validity” with examples divided into “input/output” and “processing.”
| Term | Explanation | Input/Output Example | Processing Example |
|---|---|---|---|
| Validity | The one of “input/output” or “processing” that doesn’t change after “processing” and becomes the axis for judgment | What we want to buy, natural phenomena, interface, beauty of calculation | Calculation |
| Development | The one of “input/output” or “processing” that might be changed after “processing” | Mathematical guesses | How to shop, experimentation, observation, theory, explanation, beautiful calculation |
Let me delve a bit deeper into what happens at the end of “processing” when we compare “input/output” and “processing.”
For mathematics, when making a proof, if our guess is correct, we keep it as is. If it’s wrong, we reject it. When a proof yields unexpected results, we adopt that result. Propositions that were never even considered and that have been disproven we ignore. In this way, we call it “correct” when we keep or adopt “developmental” things based on something with “validity,” and “incorrect” when we reject or ignore them3. The concrete examples of this “correctness/incorrectness” are essentially the theme of this text’s “10-fold classification of human activity.” In the mathematics example here, we assign “validity” to “processing” of “objects” called “proof” and “development” to input/output of “individuals” called “guesses,” and we call disproven propositions “incorrect” and proven propositions “correct.”
Let’s look at other concrete examples of “correctness/incorrectness.” Suppose there’s something we want to buy. This is “input/output” of “individuals.” To obtain what we want to buy, we talk to a store clerk and pay money. This is “processing” of “society.” Now suppose we forgot to present a coupon and lost money. Next time, we think about how to improve. This is an activity where we assign “validity” to input/output of “individuals” called “what we want” and “development” to processing of “society” called “how to shop,” calling forgetting the coupon “incorrect” and presenting the coupon “correct.”
For convenience in classification, when “objects” have “validity,” we call correctness/incorrectness “truth/falsehood”; when “individuals” have “validity,” we call it “beauty/ugliness”; when “society” has “validity,” we call it “good/evil.” Thus, mathematics is about “truth/falsehood,” and shopping is about “beauty/ugliness.”
Whether “correctness/incorrectness” is “truth/falsehood,” “beauty/ugliness,” or “good/evil” depends on context. Let’s examine the shopping example. Suppose we shoplifted something we wanted to buy. If we felt disgusted by ourselves and stopped shoplifting, we would consider shoplifting “ugly” and payment-based shopping “beautiful.” Conversely, some unscrupulous person who shoplifts and roleplay as a phantom thief from anime or drama might consider shoplifting “beautiful.” Changing perspective, we might consider how shoplifting harms the store and gets us arrested. If we didn’t shoplift, the feelings and attitudes of ourselves, store clerks, and police would be different. Using social norms—the input/output of “society” consisting of ourselves and others who can change—as our standard, we would call shoplifting “evil” and payment “good.” In any case, it’s context-dependent.
One thing to note is that we cannot assign “development” to “objects.” “Individuals” and “society” have one or more things we can change, so we can assign “development” to them. “Objects” have 0 changeable things. For example, without changing axioms or rules of inference, we can develop our guesses about the truth of mathematical propositions, but humans cannot change the truth value or calculation result of propositions. Of course, this is just one aspect of mathematics; we must remember that the contribution of mathematicians, the choice of axioms and rules of inference, the generalization and abstraction of theories, and the beauty of proofs are all things that can develop. However, there is an aspect where natural phenomena and proofs are fixed independently of the “agent” like humans or AI, making them “objects” to which we cannot assign “development.” To repeat, the reason is that the “agent” cannot change the input/output or processing that is “objects.”
Finally, let me summarize the terms in a table. Since the next section explains the effect of thinking about truth, goodness, and beauty separately, this is an important summary.
| Term | Explanation |
|---|---|
| Correct | Based on something with “validity,” keeping or adopting something with “development” |
| Incorrect | Based on something with “validity,” rejecting or ignoring something with “development” |
| True | “Correctness” when “validity” is in “objects” |
| False | “Incorrectness” when “validity” is in “objects” |
| Beautiful | “Correctness” when “validity” is in “individuals” |
| Ugly | “Incorrectness” when “validity” is in “individuals” |
| Good | “Correctness” when “validity” is in “society” |
| Evil | “Incorrectness” when “validity” is in “society” |
We discussed dividing “truth, goodness, and beauty.” I’ll explain what this classification means. What I’m discussing here is merely the effects. Therefore, this section is based on my empirical intuition and might have omissions or overlaps. Your opinions might differ from mine. However, I want to emphasize that the fact that classification itself is possible without omission or overlap remains unchanged. Think of this section as one example of what kind of judgments to make after classifying.
When judging “truth, goodness, and beauty,” what should we use as a standard? To that end, I introduce the following terms:
| Term | Explanation |
|---|---|
| Subjectivity | The “agent” can be changed. A quality that “individuals” and “society” have. |
| Universality | The “agent” is difficult to change. A quality that “society” and “objects” have. |
| Weight | The burden on the “agent” is large or cannot be achieved alone. A quality that “objects” and “individuals” have. |
The above qualities are constraints on activity. For example, mathematics and science are independent of us. Unlike shopping or software development, extra interpretation or decision-making doesn’t enter into our judgment of correctness/incorrectness. We’re freed from troubles and worries. Conversely, we might say that extra interpretation and decision-making in “individuals” and “society” have been constraints. In other words, according to the table above, “individuals” and “society” are constrained by “subjectivity,” while “objects” are free from “subjectivity.”
We can think similarly about “universality.” In “society” with many stakeholders and different values, it’s hard for the “agent” to change things. Things like law, custom, economy, price, and contracts are difficult to change through individual effort. You can only change them somewhat if you have some influence. And it’s impossible to change “objects” like physical or chemical laws. But imaginings or creations can be done freely by individuals. This can be rephrased as “individuals” being free from “universality.”
The same applies to “weight.” It’s easier to distribute household chores among family members than to do them alone. When sick, we can’t treat ourselves, so we have professionals treat us. “Society” serves to reduce individual burden or realize things an individual cannot do alone. “Agents” can function as distributed or parallel systems because there are multiple things we can change. According to the table, “society” is free from “weight.”
Reflecting on the discussion, the effect of dividing “correct” into “truth, goodness, and beauty” is to clarify what kind of freedom we’re thinking about. I believe that what we want to do is packed into the free parts of activity. When determining what is correct, it’s important to precisely grasp what the judgment standard is free from. For example, when shopping, we think about what we want to buy. This is something we should think about based on personal preference and individuality, so we should make “universality” freedom the judgment standard. In other words, “beauty/ugliness.” We shouldn’t be swayed too much by others when buying things. Let’s also look at the mathematics example. The truth value of a mathematical proof must not change depending on who or what proves it. This freedom from “subjectivity” has been discussed since Euclid’s Elements in ancient times, and the discussion deepened further with the collapse of naive set theory. Modern mathematics achieved freedom from “subjectivity” thanks to the great invention of undefined predicates. This is the essence of “truth/falsehood.” Society punishes violence and theft to avoid increased burden on a single victim or loss of trust that destroys the cooperative relationships of society as a whole. Freedom from “weight” seems to be the essence of “good/evil.” In summary, if you’re unsure which of “truth, goodness, and beauty” to use as your standard, think carefully about which freedom—from “subjectivity,” “universality,” or “weight”—you want to achieve. Always do this when thinking about discussions and worries.
Actually, the above discussion applies not only to “validity” but also to “development.” For example, ceremonial procedures are fixed to avoid confusion from thinking through each event from scratch. The desire is freedom from “weight.” When conducting ceremonies, however, the procedures might have “validity.” But ceremonies have developed across regions, eras, and peoples. This can be interpreted as an activity where “processing” of “individuals” has “validity” and “input/output” of “society” has “development.” In this case, we should also determine which of “subjectivity,” “universality,” and “weight” the “development” side is free from.
Based on the discussion above, let me classify human activity exhaustively without omission or overlap. This is what we call MECE. This section only confirms the names and checks that it’s MECE. Details of each activity are discussed in Various Discussion of Human Activity.
Below is the classification table of human behavior. Note that “objects” cannot be given “development” because they are unchangeable.
When assigning “validity” to “input/output” and “development” to “processing”
| “Input/Output” is “Individual” | “Input/Output” is “Society” | “Input/Output” is “Object” | |
|---|---|---|---|
| “Processing” is “Individual” | Art | Technology | Science |
| “Processing” is “Society” | Economics | Law | Science |
※ “Objects” cannot be given “development,” so they cannot become “processing” with “development”
When assigning “validity” to “processing” and “development” to “input/output”
| “Input/Output” is “Individual” | “Input/Output” is “Society” | |
|---|---|---|
| “Processing” is “Individual” | Philosophy | Culture |
| “Processing” is “Society” | Scholarship | Politics |
| “Processing” is “Object” | Mathematics | Mathematics |
※ “Objects” cannot be given “development,” so they cannot become “input/output” with “development”
Let’s verify that this is MECE. First, we consider two ways to assign “validity”: to “input/output” or “processing.” “Development” is automatically assigned to the side not given “validity.” Then we assign one of “objects,” “individuals,” or “society” to what has “validity.” We assign one of “individuals” or “society” to what has “development.” As stated in the previous section Judging Results: Truth, Goodness, and Beauty, note that we cannot assign “objects” to what has “development” because “objects” have 0 changeable things. Calculating up to this point naively gives 12 (where $2\times 3 \times 2 = 12$) types. When we look at “development” in “mathematics” and “science,” we call them the same name regardless of whether they are “individuals” or “society.” This grouping reduces it to 10 types.
The gap with the 18 types mentioned in The Structure of Human Activity: Agent, Input/Output, and Processing comes from the fact that we cannot assign “objects” to “development” and the way we name “mathematics” and “science.”
The next section will explain each classification in some detail with concrete examples.
From here, I will explain each classification with concrete examples. In addition, I will present my suggestions on how to acquire knowledge to deeply and broadly understand the validity and development of each.
Before getting into the various discussions, I offer two pieces of advice to avoid getting lost.
First, since the definitions of each “modifiable entity,” “input/output,” and “processing” were abstract, it might be hard to think of what concrete examples are. So I searched for words in existing Japanese that apply to each. I think it will be easier to understand while imagining those words. I record them in the table below. However, since these are my definitions, there might be discrepancies with traditional meanings.
| Term | Explanation |
|---|---|
| Nature | “Input/Output” of “Objects” |
| Idea | “Input/Output” of “Individuals” |
| Consensus | “Input/Output” of “Society” |
| Calculation | “Processing” of “Objects” |
| Expression | “Processing” of “Individuals” |
| Communication | “Processing” of “Society” |
The second point is about the knowledge one should acquire to organize discussions and worries. For “validity” study, I recommend “the direction of validity,” “the foundation of validity,” and “concrete examples of validity.” The former two are abstract examples divided in ways like “input/output” and “processing.” For example, with “mathematics”: “philosophy of mathematics (logicism, formalism, intuitionism, etc.),” “mathematical foundations (mathematical logic, set theory, etc.),” and “middle and high school mathematics exercises.” For “development” study, I recommend comprehensively knowing “diachronic concrete examples” and “synchronic concrete examples.” I’d like to introduce history books of each activity (diachronic) and encyclopedias that let you know comprehensively the fields currently taught in high schools and universities (synchronic). All books introduced here are from Japan.
The gap between specialists and non-specialists is dramatic, but since this text is managed on GitHub, I’ll improve it sequentially.
Activity that develops expression from ideas. From the perspective of freedom, creative ideas are developed into creative works.
This refers to music, painting, film, cooking, literature, and so on. It’s the activity of thinking how to form your idea into a work. It’s important to clarify your idea and shape it to your satisfaction.
The field of aesthetics might be important in understanding the direction of validity. To understand the foundation of validity, learning techniques and understanding their effects is good. Techniques are after all matters of expression, so focus on the effects of that expression to achieve what you want with the technique.
Music involves widely studying chord theory and instruments; painting involves studying composition and color schemes and other techniques. Museums, art galleries, and movie theaters are good places to see various works. Art history is also good. Surprisingly, common test and old-style center test Japanese literature problems can be useful. You can understand techniques in literature.
Activity that develops expression from consensus. From the perspective of freedom, creative methods are developed from perspectives that reduce social burden.
Considering quality and safety, validity should be what you agreed with users about and what their needs are. Based on requirements, specifications, and design documents, refined and individualistic products are created. The direction of validity should study quality, safety, and scientific and technological ethics. Reading books on software engineering, mechanical engineering, and materials engineering is good for foundations. Especially software engineering loves talking about development processes like agile and waterfall, which is helpful.
For technical development, look for illustrated dictionaries of how scientific technology works. I found a book called “Technology Mechanisms and How They Work Illustrated Dictionary” to be quite good. My definition of “technology” includes agriculture, medicine, and pharmacology, so developing interest in those jobs is also worthwhile. There are quite a few history books on technology.
Activity that develops expression or communication from nature. From the perspective of freedom, we change our actions based on phenomena we cannot change.
Note that this refers to science, not scientific technology, but rather science education. When considering science this way, it includes hobbies and educational activities.
Natural laws are things humans cannot change. They occur outside humans.
Experimentation and observation should be done carefully and incorporated into explanations or theories where the same things happen regardless of who does them. For example, when we look at the surface of living things with a microscope, we see small units called cells. On Earth, objects fall with the same acceleration regardless of mass in a vacuum. However, if we’re too far from Earth, we need to apply the law of universal gravitation because that no longer approximates. All these have their “truth/falsehood” determined by experiment and observation. If you think you’re wrong, experiment and observe. There’s a lot of talk about relativity and quantum mechanics in popular media, but without understanding what experiments or observations led to such thinking, you’ve understood nothing.
The direction of validity in science has been discussed to death. The field of philosophy of science has tons of information. It’s also in obligatory education textbooks. Study well the discussions of “reproducibility” and “falsifiability.” However, there is discussion in philosophy of science that confuses the following “scholarship” and “science”. Examples include the sociology of science and paradigms. Be careful.
For the foundation of validity in science, widely knowing methods of experiment and observation is important. If I were to give a good representative example, understanding how physical units have been decided through history and measurement is good. Understanding the laws and experiments underlying units like A (ampere), C (coulomb), and K (kelvin) makes a big difference. Moreover, if you can intuitively understand what 10kg or 10mA means through your senses, that’s even better.
For scientific development, I recommend studying the history of chemistry and the history of electromagnetism. You can see extremely well how invisible natural phenomena came to be understood. Also, high school science reference materials are recommended for broadly knowing science. Becoming expert in high school physics, chemistry, biology, and earth science within the Japanese curriculum should make you quite formidable. Physics alone is impossible to do due to mathematics, so studying at the university level is essential.
I’ll add this for clarity: “scientific technology” is not “science.” It’s “technology” applying insights from “science,” and the “validity” is not “nature” but “consensus.” Because you’re making things, what you want to make you’ll decide through discussion with yourself and others.
Activity that develops communication from ideas. From the perspective of freedom, individual actions to reduce social burden are developed from personal thoughts.
Note that this refers to economic activity, not economic systems.
Following personal purposes and communicating to obtain something. This is all economic activity. As evidence, game theory is a branch of economics. We satisfy our personal desires through the help of others. Currency is a wonderful invention—as a medium of communication when asking others to provide goods or services, it’s supremely useful. Without troublesome negotiation, we can get coffee by paying money. Currency is probably the greatest achievement in communication media.
Without obsessing over currency, we can provide goods or services based only on trust and love, and do give-and-take. This is also legitimate economics.
I don’t know what to reference regarding the validity of economics. We might be able to view management philosophies as a type of “input/output” of “individuals” with “validity.” There are books about the effects of management philosophies and how to have them. But it seems aesthetics as consumers haven’t been much discussed. Well, perhaps we should just negotiate and shop freely as we like. In any case, I haven’t found anything systematically describing the “beauty” of “economics” in my definition.
There’s plenty in the development direction. It might be good to study economic thought well first. Both capitalist and socialist systems are evolved means of communication. Heterodox economics, when well studied, seems to broaden and deepen understanding. Economic history and history of economics are very important. Rather than focusing on pseudo-scientific economic mathematics, you should look at the historical development of economics and think about what means of communication we should develop. When beings like AI or robots that exceed human ability appear, how economic means among humans change is something to think hard about. It’s also good to study negotiation techniques, management, leadership, micro and macro economics, and so on. High school political economy reference materials are quite good.
As a tangent, “economics” looks like “science” because it uses lots of mathematics, but the axioms of that mathematics come from ideology, not experiment. Even if we actually investigated, “society” is something that changes through media manipulation or political governance. Do people who think of economics as “science” really not change economic means? At least economics in my definition is not “science.” However, it is “scholarship,” discussed later.
Activity that develops communication from consensus. From the perspective of freedom, solving problems with less burdensome methods based on ways of thinking that reduce burden.
Note this refers to justice and jurisprudence, not legislation.
Interpreting and coordinating rules decided by nations, local governments, companies, schools, families, and other organizations is legal activity. Social norms and agreements are constrained by “universality,” but we can achieve freedom from “weight.”
Saying “less burdensome methods” when difficult bar exams make this linguistically strange. This means that in a world without case law, scholarship, and the legal codes, thinking the same way from scratch is “less burdensome” than lawyers.
The direction of validity should study jurisprudence, and reading books on legal interpretation is good for foundations. Thinking about justice, responsibility, fairness, impartiality, equality, and so on and learning proper legal interpretation through case law and scholarship can help non-lawyers convince others more easily.
For development, introductory books on legal codes, comparative law, and legal history are good. There seem to be two frameworks: becoming expert domestically and comparing different nations.
Activity that develops ideas from expression. From the perspective of freedom, ways of thinking are refined through creative methods.
Humans all do this: changing your own thinking based on your own experience and actions.
What did great figures of the past think, and about what? High school ethics reference materials are excellent for understanding their validity and development.
Activity that develops consensus from expression. From the perspective of freedom, ways of reducing social burden or achieving things in groups are developed through creative methods.
Music, anime, dramas and so on change what trends in society. The society that develops in this process is culture. Developing culture through cultural activity. Sharing enjoyment with friends and family or appreciating others’ works and activities cannot be achieved alone. In a sense, it reduces social burden.
Without ceremonial procedures, we might be at a loss for what to do when something special happens. The form changes across countries, regions, and eras, but fixing the action guidelines for special days reduces social burden in a sense.
I don’t know what to reference when thinking about the beauty of culture. Cultural relativism is often negated, and there’s lots of discussion that doesn’t distinguish “beauty” from “truth.”
For development, there’s mountains of material. Illustrated Japanese folklore, ceremonial etiquette, books about Japanese language are recommended domestically. To broadly see internationally, high school geography and cultural anthropology are recommended. Cultural history books abound. Folklore studies also have a strong historical aspect. Most of all, appreciating contemporary entertainment and everyday life alone helps you understand development to some extent.
Activity that develops ideas from communication. From the perspective of freedom, it’s a means where individual thinking is refined through less burdensome methods.
Rather than thinking everything from scratch, we refine individual thinking through past literature and discussion—textbooks, papers, historical documents, etc. If we view the “agent” as the academic community, it also means development of new fields themselves. Past or present communication with self or others serves as the “validity.” Also, “scholarship” seems to be classified as “education” when teachers teach known things, “learning” when students learn, and “research” when dealing with unknown things.
“Scholarship” is easily confused with “science.” For example, developing hypotheses is often more influenced by “communication” than by “nature.” History and paleontology are storms of interpretation of documents and materials, which we should think of less as “nature,” which is “objects,” and more as “communication” between ourselves and others that can be changed through interpretation, serving as “validity.” Biological taxonomy and scientific nomenclature are “scholarship,” not “science,” because how we name things, whether things are named, classification procedures, etc. are decided by “communication,” not “nature.” “Scientific research” is not “science.” Even in fields like science, researchers must read past papers and claim novelty and progress. Whether we can explain well to experts determines some aspects. Explanation is a dialogue between changeable self and others, so this is “communication,” not “nature.”
“Validity” foundations can be built through studying study skills and academic writing. For the direction of “validity,” studying research ethics and library science might be good. You might think about why we should cite, why fabrication is wrong, and what documents are.
For “development,” Wikipedia’s list of disciplines is surprisingly good. Books exist, but sadly lack comprehensiveness. For historical development, following the history of universities and humanities helps quite a bit.
Activity that develops consensus from communication. From the perspective of freedom, changing ways of thinking that reduce burden through less burdensome methods.
Examples make it clearer: voting, demonstrations, mass media that change welfare and economy. Politics is certainly troublesome and difficult, but voting systems, demonstration know-how, and means like propaganda that gather cooperation with less trouble seem to reduce burden. Above all, society isn’t moved easily by one person. Power is an excellent communication medium; rather than hearing everyone’s opinion, which takes too long, a small group can decide quickly. This power is probably an important concept supporting “validity.” That military force can change the state of the world in ways that are naturally classified as “politics” when thinking of it as “input/output” and “processing” between multiple nations.
For the direction of “validity,” political philosophy seems good. For political foundations, studying political process, or electoral and voting systems and game theoretic models of public choice is good.
For political development, “Yamakawa World History,” “Yamakawa Japanese History,” and high school political economy reference materials are recommended.
Activity that develops ideas or consensus from calculation. From the perspective of freedom, ways of thinking of individuals and society are changed through methods independent of interpretation or decision-making.
The history of “validity” in mathematics is wonderful. From Euclid’s Elements to the emergence and collapse of set theory to the birth of modern mathematics—it’s dramatic and philosophical. Modern mathematics is simply amazing. The idea theory of “a line is a long line with width 0” is unnecessary. That’s “philosophy.” When we say “line,” you’re free to imagine elementary geometry or $y=ax+b$. The great invention of undefined predicates made truth verification depend only on mechanical manipulation of axioms and rules of inference, eliminating the need for correspondence with reality or interpretation. When you see $1+1=2$, you’re free to imagine two apples or two oranges. When you hear natural numbers, you’re free to imagine decimal, binary, Roman numerals, or Chinese numerals. Whether natural numbers start from 0 or 1 doesn’t matter. All the natural numbers mentioned above satisfy Peano’s axioms. In this way, the trial-and-error “processing” part can be “objects.” Thanks to Cantor, Brouwer, Russell, Hilbert, and many other mathematicians.
I want to discuss “Gödel’s Incompleteness Theorems” here. People often misunderstand “Gödel’s Incompleteness Theorems” and make terrible claims like “There are propositions in mathematics whose truth value is undetermined. Mathematics is an incomplete discipline!”
There certainly are problems in mathematics whose truth value is undetermined. But that wasn’t shown by “Gödel’s Incompleteness Theorems.” There’s a simpler example. For instance, whether the commutative law of a group or its negation can be derived from the group axioms. The answer is no. Because both the integers with addition where the commutative law holds and non-commutative regular 2×2 matrices with multiplication both satisfy the group axioms4. It’s neither true nor false. But there’s no need to be pessimistic. We can use different axioms depending on purpose. The decision of whether to include the commutative law is made by “science” or “scholarship” or “philosophy”… In any case, not “mathematics.” But the part where “truth/falsehood” is determined is certainly “objects,” and the part where truth value is undetermined has high degrees of freedom from “universality.”
“Gödel’s Incompleteness Theorems” says that when axioms include natural numbers (or something like them), the consistency of that system cannot be shown within the system. First, the proposition itself is quite special—it’s doing in logic what happens when an emulator runs on a computer. The computer is saying about an emulator that it can’t prove within itself that it’s consistent, or its negation. However, this means that by adding certain axioms, an emulator can say it’s “inconsistent” or “consistent.” Using the same method as the commutative law of groups, if we add an independent axiom claiming “consistent,” there’s no problem. However, the prerequisite is that we can discover that axiom, which is quite difficult.
The direction of “validity” should know the philosophy and history from naive set theory to the birth of modern mathematics. For foundations, studying mathematical logic, set theory, theory of computation, and other mathematical foundations and computer science is good.
For mathematical development, first start from high school mathematics. Then read Koga’s “Map of the Mathematical World.”
Calculation on computers—if we view computer and user as one “agent,” it’s “mathematics.” If the computer has the ability to make guesses like generative AI, the computer alone is the “agent.”
So far, I’ve explained the classification method. I’ve tried to convey a classification that seems useful for organizing discussions and worries. And if you feel interested and think “I want to use this way of thinking!” that would make me very happy.
However, there are several cautions when using this classification method. Let me discuss them.
The classification introduced here is merely for organizing discussions and worries. It certainly does not rank things as superior or inferior or fit them into categories. It does not determine the qualities of specific people or things. It merely clarifies context and interpretation.
Also, as we’ve seen, the way classification is done changes with context and interpretation. You should flexibly change classification to suit the topic. However, even if classification changes flexibly, it’s guaranteed to fall into one of the 10 categories. The classification itself has no excess or deficiency.
Finally, I want to emphasize that “agent” and “individual” are different things. For example, in Descartes’ mind-body dualism, the “mind” is the “agent” and the “body” is the “individual.” In another example, the “programmer” is the “agent” and “programming” is the “individual.” When imagining something, the “brain” is the “agent” and the “imagination” is the “individual.” In this way, the “agent” is the side that changes, and the “individual” is the side that gets changed. Be careful.
Let me discuss the subsidiary effects of this classification.
First, by comprehensively viewing and defining relationships from the whole, certain things become clear. For example, the definition of “culture” was vague, but by classifying exhaustively without omission or overlap and positioning it in the whole, its definition became clear. Also, it appears that “culture’s” “validity” is an “individual” “input/output,” and “beauty/ugliness” is the judgment standard. From this, the importance of the question “What is beauty in culture?” became clear.
Second, abstraction has generated new questions. For example, does satisfying desires through theft and violence count as a type of economic activity? It’s wealth redistribution, but by abstracting “economics” to the act of developing “society’s” “processing” based on “individuals’” “input/output,” we could ask the question. Conversely, refining desires through theft and violence—is that “scholarship”? My answer is that these are “ugly” or “evil” classifications of “economics” and “scholarship” that have been rejected or ignored. Though they can be considered a type, for some reason they’ve been judged “incorrect.”
Finally, the effect I want to emphasize is that thanks to structural abstraction, although we say “human activity,” we can apply it beyond humans. For example, we can include home appliances and pets as part of “society.” Learning to operate appliances or communicating with pets can be viewed as “society.” Moreover, if there is “input/output” and “processing,” and behavior changes accordingly, everything is an “agent.” This makes it possible to define “economics” or “scholarship” with AI and robots as agents, and I think it’s an essential skill for people in 2026 to think about the future.
So far, I’ve discussed classification of human activity for organizing discussions and worries. Classification begins by dividing “human activity” into three: “agent,” “input/output,” and “processing.” Then we assign “validity” to one of “input/output” or “processing” and “development” to the other. Then we assign “objects,” “individuals,” or “society” to “validity” and “individuals” or “society” to “development.” The strength is that we can classify flexibly depending on context yet exhaustively without omission or overlap—something will fit into one category.
The trick when classifying is understanding what freedom from “subjectivity,” “universality,” or “weight” you want. Which freedom’s “validity” should be paired with which freedom’s “development”? I think the ability to grasp this is quite important.
Also, a major achievement of this “classification of human activity” was that by comprehensively viewing abstractly and positioning within the whole, we achieved “clarification of definitions,” “creation of new questions,” and “extension beyond humans.”
Detailed topics touched on in this chapter are described in Advanced Edition. In How to Live in the AI and Robot Age, we’ll discuss how to live in the AI and robot age based on Fundamentals and Advanced Edition.
The essay I started writing before refining this idea is here. It ended up incomplete because I couldn’t organize my thoughts well, but there are lots of ideas. I also have notes at about the memo level. It’s not something people can easily read, but if you’re interested, please do.
Finally. This text has no citations or references. Frankly, its value as an academic paper is limited. However, I believe this idea will become philosophically significant through refinement. If you felt any value in the “10-fold Classification of Human Activity” described in this text, I would appreciate your collaboration. I’d be delighted to receive pull requests on GitHub, etc.
I hope my thinking will be useful to someone.
The Advanced Edition is planned to cover the following, but is currently in preparation:
Main text
Before refinement
Math experts might prefer axioms and rules of inference, but I prioritized understandability and familiarity in how I explained it. ↩
Of course, there can be different proofs even if truth value is the same. If focusing on beauty or elegance of calculation, you might interpret changeable things as 1 or more. That’s context-dependent. Details are in the same section as this note. ↩
I use “retain” and “adopt” for known things, “adopt” and “ignore” for unknown things. ↩
I think studying the relationship between proof theory and semantics in mathematical logic will help you understand. ↩