無人販売は「性善説」なのか？ #192

Unmanned Stands, Self-Checkout, and the Phrase "Human Nature Is Good"

Unmanned roadside vegetable stands and supermarket self-checkout lanes both leave payment entirely to the customer's conscience, and they are routinely cited in Japan as proof that Japanese society is built on the assumption that people are good. Vending machines surviving undamaged in rural areas are offered as further evidence of the same idea.

The variety show *Suiyōbi no Downtown* once ran a segment verifying unmanned stands: in many cases the farmer checked the cash box and simply assumed sales had been brisk, never suspecting theft. Fukai (深井) noted that the show's very premise — testing whether the farmer would suspect theft — was itself an unusually cynical hypothesis.

On self-checkout, Fukai recalled feeling "trusted too much" when a late-night convenience-store clerk disappeared into the back room while he stood at the register. Higuchi (樋口) pushed the theme further, arguing that leaving a parking-payment terminal on its home screen, abandoning a bookstore inventory terminal mid-search so the title you looked up is visible to the next customer, and leaving your self-checkout receipt for the next person to deal with all count as "making the other party do one extra step" — a form of rudeness. Fukai responded with amused disbelief.

Confucius's Position — Same Nature for Everyone, Differences Come from Environment

According to Fukai's account, Confucius took the position that all human beings are born with the same nature (xìng) and largely declined to theorize about what that nature contains. Because he saw every difference in values and character as the product of education and habit, the main subject was not shared essence but "the education that produces difference." Fukai illustrated this with the lyric "because we grew up in different environments" (from the Japanese song *Serori*). He also observed that the urge to derive a single universal essence is "somewhat Western-philosophical" in flavor.

Mencius's Theory — The Four Sprouts as Seeds of Goodness

Several generations after Confucius, Mencius advanced the theory that human nature is good, while Xunzi argued the opposite. Because the thinkers of the period were primarily concerned with education and governance, they needed to explain why humans can act well or fall into wrongdoing — which led to the unusual move of applying a moral evaluation to nature itself.

Mencius's core claim is not that people arrive in the world already virtuous. His argument is that every human being possesses the sìduān (四端) — four emotional sprouts: ① cèyǐn (惻隠), compassion for others; ② xiūchǐ (羞恥), the sense of shame; ③ círàng (辞譲), the impulse to yield and defer; and ④ shìfēi (是非), the ability to distinguish right from wrong. These are only sprouts; Confucian education is required to cultivate them into full virtue.

Applied to the unmanned vegetable stand: feeling sorry for the farmer who spent a year growing the crop corresponds to cèyǐn; finding it shameful to take produce without paying maps onto xiūchǐ; judging that the rules require payment is shìfēi. From this angle, Fukai concluded that the popular claim "unmanned stands rest on the goodness-of-human-nature theory" is about 60% wrong but not entirely off the mark — roughly 40% defensible.

Xunzi's Theory — Goodness as the Artificial "Wèi"

Xunzi held that the love of self-interest and the tendency to envy others are the natural emotional baseline of human beings. Viewed against the backdrop of a natural world governed by the strong preying on the weak, self-preservation and jealousy are the more original drives. Goodness therefore does not arise spontaneously; it is acquired after the fact through ritual and education. Xunzi captured this with the character 偽 (wèi) — written by combining the characters for "person" (人) and "action" (為) — meaning deliberately engineered human conduct.

Fukai pointed out that both theories arrive at the same conclusion: because the good-nature theory says the sprouts must be cultivated, and the evil-nature theory says the evil must be corrected, both end up at "therefore education is necessary." He also noted the paradox that taking either extreme literally — all people are fully good, or fully evil — would actually eliminate the need for education.

The Ring of Gyges and the Basis of Morality

The Ring of Gyges thought experiment from Plato's *Republic* asks how a person would behave if a ring made them invisible, removing all risk of discovery or retaliation. The text concludes that people would ultimately do whatever they pleased, suggesting that human nature is fundamentally self-interested.

Higuchi pushed back: there is never truly zero risk, because the victim might grow angry and retaliate. He then added the Men in Black neuralyzer — a memory-erasing device — to the scenario: even if every piece of evidence and every witness's memory could be wiped, "you cannot erase your own memory of having stolen. Even if no one finds out, it doesn't feel comfortable." Fukai mapped this lingering guilt onto the Mencian sprouts of shame (xiūchǐ) and moral judgment (shìfēi), while noting that the alternative logic — "I won't do it because getting caught would be a net negative" — aligns instead with Xunzi's self-interest framework.

The conversation closed with the difficulty of grounding moral obligations without religious backing — using "why must we take care of our possessions?" as an example. A consumer economy arguably profits more when people discard things quickly, which means any attempt to attach a reason to "this is good" immediately sounds strained. Fukai concluded that it is precisely in that explanatory difficulty that both the good-nature and evil-nature theories found their historical purpose.