Re: [討論] 如果昨天到了明天會變成兩天前

[MathTurtle (恩典)]

okok...我去看了一下, 覺得滿有趣的, 和哲學中在討論的時間哲學有些相關。

原文似乎是:
"If yesterday was two days ago tomorrow,
will the day after tomorrow be today or yesterday?"

其實關鍵在於時態。

首先有個小問題, 為何第一句用 'was'?
按照正常的文法, 第一句的時間是由副詞tomorrow給出,
而不是由主詞yesterday給出, 所以按文法規定而言可以有:
1. if yesterday will be two days ago tomorrow...
   這是最直接的講法。
   意思是, 在明天時, 昨天「是」兩天前。

2. if yesterday is two days ago tomorrow...
   這樣也可以通, 因為未來時態的condition有時可用現在式,
   表達對fulfillment的不確定性 (e.g. if it rains, I will stay home).
   另一種會用 'is' 的原因是表達tenseless的條件,
   也就是單純呈述昨天(indexical)是兩天前(non-indexical)。

3. if yesterday were two days ago tomorrow...
   這種講法也有可能, 這裡的were是subjunctive,
   基本上是表達與現在事實相反的counterfactual 假設,
   不過也不一定要預設與現在事實相反, 單純只是表達counterfactual,
   不過如此的語態後面那句也要改, 就變成:
   if yesterday were two days ago tomorrow,
   would the day after tomorrow be (or have been) today or yesterday?

好, 現在, 時間哲學當中有兩個理論,
tensed theory 和 tenseless theory.

根據tensed theory, if yesterday will be two days ago tomorrow,
(of course it will, but the tensed phrase clearly indicate such a context),
then the day after tomorrow surely will be today, it also will be yesterday,
but on a different day.

根據tenseless theory, if yesterday is two days ago tomorrow,
(the conditional indicates the context where we may translate the indexicals),
then the day after tomorrow is tomorrow (index = tomorrow),
it cannot be today, nor yesterday, and of course it cannot be both.

大概是這樣, 我在學時間哲學時, 感受到英語母語人士對時態語感的強列依賴,
如果持定tense theory, 很難理解tenseless theory 的觀點,
反過來, 如果持定tenseless theory, 也難理解tense theory 的觀點。


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推 aletheia:我不太懂為什麼tensed的時態要用will be
推 aletheia:tenseless要用is?
→ MathTurtle:tenseless只是陳述material implication中的前件
推 hirabbitt:強大...到我看不懂XD 數龜什麼都學嗎
推 ars1an:你後面的說明我可以理解，但回過頭來看反而題目很奇怪
→ ars1an:If yesterday "was"..., "will"....
→ ars1an:這樣的問句是tensed theory還是tenseless theory?
推 H45:有人和我一樣從 tensed, annd tenseless theory 聯想到微軟中
→ H45:國研究院最新面試題的討論串嗎....
推 hirabbitt:哪題0.0?