Why two 不 in 不得不, when only one "not" in its English translations?

Question

MDBG and ZDIC translate 不得不 as

have no choice or option but to, cannot but, have to, can't help it, can't avoid

"Have to" contains no negator particles! All other translations have merely one negator, either "no" or "not"! Thus why does Chinese have two negators in 不得不?

Answer 1

"have to" contains no negator particles! All other translations have merely 1 negator, either "no" or "not"! Thus why does Chinese have 2 negators in 不得不?

"不得不" is another way to say "一定要" (certainly have to)

要 has the meaning of "have to"

"不得" is a tightly bonded term that we treat like a compound word, which means "not allow/ cannot" in Chinese. e.g. 不得進入 (not allow to enter)

You can see 不得 as the literal form of 不可以 (can't/ not allow)

"不得不" (cannot not to) = not allowed to not" -- It means the same as 一定要(certainly have to) in which 一定 is a compound word

Although "不得不" (not allow not to) means the same as "一定要" (certainly have to/ must), "不得不" emphasizes the 'no choice' aspect more

Edit:

IONQ wrote

Thanks. ""不得不" (cannot not to) = not allowed to not" -- It means the same as 一定要(certainly have to) in which 一定 is a compound word" Can you pls elaborate? How do they mean the same?

I should say they mean the same by logical deduction.

• If you are not allowed to not do something, then it is something you must do.

• If you must do something, then you are not allowed to not doing it

Example:

不得不去 (not allowed to not go) = 一定要去 (must go)

Answer 2

On the English side, please note that:

1. Negation is implied in the preposition "but":

have no choice or option but to,
cannot but,
can't help it (but)

2. Negation is implied in the verb avoid:

can't avoid

3. Two negations equal to affirmation:

have to

Answer 3

You can split 不得不 to 不得 and 不.

不得 means "no choice", "must not".

So 不得不 means "only one choice", "must".