にせよ details
even if; whether — a case granted in writing, and denied any effect on the conclusion
理由がどうであるにせよ、無断の欠席は認められません。
riyuu ga dou de aru ni seyo, mudan no kesseki wa mitomeraremasen.
Whatever the reason may be, an unexcused absence cannot be permitted. formal
冗談にせよ、あの言い方はさすがにひどい。
joudan ni seyo, ano iikata wa sasuga ni hidoi.
Even if it was a joke, that way of putting it really was too much. neutral
- colloquial
Examples
even if; whether it is so or not — one case granted, and the main claim held to regardless
理由がどうであるにせよ、無断の欠席は認められません。
riyuu ga dou de aru ni seyo, mudan no kesseki wa mitomeraremasen.
Whatever the reason may be, an unexcused absence cannot be permitted. formal
冗談にせよ、あの言い方はさすがにひどい。
joudan ni seyo, ano iikata wa sasuga ni hidoi.
Even if it was a joke, that way of putting it really was too much. neutral
手伝うにせよ、まずは事情を聞く必要がある。
tetsudau ni seyo, mazu wa jijou o kiku hitsuyou ga aru.
Even if we are going to help, we need to hear what happened first. neutral
いずれにせよ、今日中には決めなきゃ。
izure ni seyo, kyoujuu ni wa kimenakya.
Either way, we've got to decide before the day is out. casual
予算の制約があるにせよ、安全対策を削ることはできかねます。
yosan no seiyaku ga aru ni seyo, anzentaisaku o kezuru koto wa dekikanemasu.
Even granting the budget constraints, we are not in a position to cut safety measures. formal
Formation
plain clause + にせよattaches to plain clause{N}にせよattaches to noun
Variant notes
- にしろ — the same frame on する's colloquial imperative しろ — blunter, at home in speech, where にせよ belongs to written argument. 冗談にしろ、言い過ぎだ。
Notes
(不便であるにせよ). いずれにせよ・どちらにせよ have frozen into "in any
case" and no longer grant a specific case at all.
Related patterns
Similar
にしても is the register-neutral member of the family and sits in any conversation; にせよ rides せよ, する's literary imperative, and belongs to written argument and prepared formal speech — putting にせよ into casual chat reads as posturing, which にしても never does.
としても frames its material as a constructed SUPPOSITION and needs a full predicate in front, so a noun must take だ (冗談だとしても); にせよ takes the bare noun directly (冗談にせよ) and grants a case that may well be true rather than posing one for argument.
とはいえ concedes something already on the table and can open a fresh sentence with the concession left behind in the previous one; にせよ must keep its own clause in front of it inside one sentence, and what it grants is typically still unsettled (理由がどうであるにせよ).
Both are written concessives, and they take different material — にせよ grants a whole proposition or a bare noun (冗談にせよ), while とも attaches only to the volitional or to an i-adjective stem, so it can never take a bare noun (×冗談とも).
Lookalikes
A lone にしろ is にせよ's colloquial twin and merely GRANTS one case; doubled, にしろ〜にしろ stops conceding and ENUMERATES the alternatives it claims to exhaust — so the second にしろ is what fixes the reading, and meeting the first one mid-sentence settles nothing yet.