举个例子，两个人申请同一职位，他们在那职位上的能力相同，但其中一人可能会因为他的性别／年龄／种族而不被取录，那就构成性别／年龄／种族歧视。
为什么这是一个道德问题？
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資訊和交通越來越發達，種族歧視和現代社會越來越格格不入，現在仍然以「種族」的理由對不同顏色的人有不同的待遇，誠然是很「老土」的。
另方面，在國与國之間的交接面仍然有很多矛盾，例如香港仍然有很多人罵大陸人是蝗蟲。 無他，大量人口的移動 disrupt 了原居民的日常生活，甚至佔據了他們的土地，令那些人抱怨，而他們並不是什麼政治理論的專家。
根據「種族主義已經過時」的趨勢分析，我們應該正在邁向世界大同的方向才對； 但國際上的政治現實卻似乎向另一方向發展。 這是矛盾的，為什麼有此現象？
經過了多年的思考，我發覺問題的癥結可以叫做 "ahistorical fallacy"。 亦即是說，我假設世界的發展方向和過去的歷史無關，但那是不對的。 例如很多中國人仍記著南京大屠殺、慰安婦等事件，日本人仍然每年在哀掉原子彈爆炸，似乎不可能叫人們忘記過去。
（但據說，很多年青一代的越南人似乎沒有因為越戰而仇視美國人。 我想，可能是因為他們是戰勝國，至少在官式上他們戰勝了，而實際上他們也趕走了殖民主義。 我不清楚越南現時的政治，但至少他們是自己管自己的。 有人說越戰是螞蟻和大象的戰爭，而很奇跡地螞蟻戰勝了，當然實際上有中共和蘇聯在背後。）
因為歷史的糾結，令世界統一變得好像不太可能，這令我想起傳說中無法解開的 Gordian knot，雖然 Alexander the great 用武力把它斬開了，但他的帝國也不長久。
曾經有很長的一段時間，我很疑惑： 一方面種族歧視已經過時，但另方面世界統一卻因為歷史因素而顯得不可能。 這令我想起聖經《創世記》裡有一則故事： 上帝要消滅 Sodom 這座城市，但 Lot's wife 在逃難時違背了神的指示而向後看，結果她變了一條鹽柱。
我得到的啟發是： 如果我們總是朝著後面看，則一切新的發展都顯得沒有可能。 但如果向前看的話，歷史進步的方向是很明顯的。
『活著的人絕對不可服務已死的人，但已死的人，如可能的話，可以服務活著的人。』 --- Philip K Dick, A Scanner Darkly
=============== English translation ================
As transportation and communication become advanced in our world, the idea of racial discrimination is getting more and more incompatible with modern sensibilities. Discriminating people based on color is getting very out-of-fashion.
On the other hand, there is still a lot of conflicts at the interface between nations. For example many Hong Kong people still refer to mainland immigrants as "Locusts". This is not hard to understand: massive population migration disrupts the lifestyle of original people, even occupying their land, causing the natives to protest, who are not well-versed in political theory.
According to the idea that racism is out-dated, we should be heading towards a stage of global unification; However the political reality in the current international scene seems moving in the opposite direction. This is contradictory; why is it so?
After many years of thinking, I found the crux of the problem could be called the "ahistorical fallacy". That is to say, I assumed the development of world affairs to be independent of history, but that is incorrect. For instance, many Chinese still remember the Nanjing massacre and the prostitutes of war, and every year the Japanese still mourn the dropping of the atomic bomb. It seems that we cannot tell people to forget the past.
(But I have heard that the younger generation of Vietnamese generally do not bear a grudge against Americans for the Vietnam war. I guess this might be because they have won the war, at least officially so. Indeed, they succeeded in expelling colonialism from their country. I don't know much about current Vietnam politics, but at least they are ruling themselves. Some say the Vietnam war is a war of ants against an elephant, but the ants miraculously won, though of course there was the backing from communist China and the Soviet.)
Due to the entanglement of history, world unification seems implausible. This reminds me of the Gordian Knot, and Alexander the great famously cut it with brute force, but his empire didn't last long.
For a long time, I was perplexed: on the one hand racism is out-dated, on the other hand world unification is unlikely due to historical factors. This made me think of the story from Genesis: God decided to destroy Sodom, Lot's wife disobeyed God's instruction and looked back, turned into a pillar of salt.
The lesson I got from this: if we keep looking back, then all new developments would seem impossible. But if we could look forward, the direction of history's progress is very obvious.
"The living should never be used to serve the purposes of the dead, but the dead should, if possible, serve the purposes of the living." --- Philip K Dick, A Scanner Darkly
