事後才出現的判斷
第二次的猜落在結果後面，於是它變成評語：憑現在才知道的事，去評當時的決定。
verb · C1
To say, after something has already happened, that a decision was wrong or that you would have done it better — including when you keep doubting your own past choices.
事後質疑
核心畫面
You can think of second-guess as a second guess laid on top of someone's first one. Somebody has to decide, and does. Then a second person — or the same person later — puts down their own version of that decision. If the second guess lands after the result is known, it is the judgement of the : I would have done better. If it lands before, you are trying to read a decision that has not been made yet, with nothing to go on but the other person. The word is always about that extra guess, and about who made it, and when.
「second-guess」可以想成在別人的第一個判斷上面，再壓一個自己的判斷。有人得做決定，他做了。接著第二個人—…更多收起
「second-guess」可以想成在別人的第一個判斷上面，再壓一個自己的判斷。有人得做決定，他做了。接著第二個人——或同一個人過一陣子——把自己的版本擺上去。如果這第二次的猜是在結果揭曉之後才出現，那就是場邊的評語：換我會做得更好。如果是在決定之前，那就是在讀一個還沒發生的決定，手上除了對方什麼都沒有。這個字講的永遠是那多出來的一次猜：誰猜的，以及什麼時候猜的。From the word’s history
The Wiktionary entry records second-guess as a back-formation from second guesser, originally from baseball, with first use around 1941 — the onlooker who names the better play once the ball has already been thrown.
來源資料記載這個字是從 second guesser 倒推出來的，最早出現在美國棒球場上，大約一九四一年開始使用：球已經打出去，場邊的人才說出他那個「更好的一球」。這個畫面正好解釋了今天兩個用法的重點都在時間點。
Wiktionary entry for second-guess, etymology field: A back-formation from second guesser, originally from baseball. First use appears c. 1941 (packet source_ref kaikki:3f6f69a190036ae4:917342088:9381)
Two branches
事前搶先的猜測
同樣是那多出來的一次猜，只是被挪到決定之前：你搶在對方開口以前，先替他猜。
verb · C1
To try to work out in advance what someone will decide or do, or what will happen, when you can only guess.
預先揣測