確かに|たしかに

1. 1Certainly, indeed: affirms a fact or agrees with a statement.Ex. 2
2. 2Admittedly, it's true that…: concedes a point before a contrasting 'but' statement.Ex. 1

A neutral adverb common in both conversation and writing, used to agree with a remark or to acknowledge a point before countering it. In the concessive frame, 確かに only marks the concession. The contrast comes from a following connector such as が, けれど, しかし or でも, unlike conjunctive patterns such as ものの or とはいえ, which carry the 'but' themselves.

• 〜こそ〜がN3Similar to 「確かに」 only in its concessive sense. 「〜こそ〜が」 inserts 「こそ」 after a noun, the masu-stem, etc., to acknowledge only that point with a stronger contrast, while 「確かに」 is an adverb that concedes the whole sentence; rewriting is possible only when there is an element that can be marked with 「こそ」.
• もののN2Similar to 「確かに」 only in its concessive sense. 「ものの」 attaches after a predicate and expresses contrast on its own, tending toward written style with a second clause that often falls short of expectations, whereas 「確かに」 is an adverb that needs 「が／けれど／しかし」 and the like to create a contrast, and is used to first agree and then offer one's own view.
• とはいえN1Similar to 「確かに」 only in its concessive sense. 「確かに」 is an adverb whose contrast depends on a following 「が／けれど」, while 「とはいえ」 expresses contrast by itself, attaching after the first clause or standing at the start of a sentence, with a somewhat written-style tone.
• とはいうもののN1Corresponds only to the concessive sense of 「確かに」. 「とはいうものの」 carries its own contrast, attaches after the previous sentence or stands at the start of a sentence without adding 「が」, and leans toward written style, whereas 「確かに」 relies on 「が／けれど／しかし」 for contrast and can also express confirmation or agreement.
• もっともN2When 「確かに」 marks concession, it first acknowledges a point and then turns to the speaker's claim with 「が」 and the like, with the focus on what follows; 「もっとも」 is a conjunctive placed at the head of the following sentence to add a limitation or reservation to the preceding judgment, with the focus on what comes before. The two cannot be swapped.
• こそあれN3Similar only in the concessive sense; they are not interchangeable. 「こそあれ」 attaches to nouns and adjectives (i-adjectives take the く form), carries its own contrast, and belongs to written language, whereas 「確かに」 is an adverb that needs 「が／けれど」 for contrast, is neutral in register, and can also express confirmation on its own.

確かに is an adverb that opens a concession and needs a separate contrastive connector (が, けれど, しかし, etc.), whereas ものの, とはいえ and とはいうものの are themselves the concessive link (and more formal), and もっとも adds a qualifying afterthought after a statement. 〜こそ〜が and the literary こそあれ emphasize the conceded element itself rather than simply acknowledging a fact.