for that matterありました

虚数の√-1をイメージできるようになる、という
"Imaging Numbers (Particularly the Square Root of Minus Fifteen" by Barry Mazur (Penguin Mathematics, ISBN:0141008873)
という本を骨を折りながら読んでいたら、"for that matter" に遭遇しました。
「使える」かどうかわかりませんが、ちょっと長めに引用しておきます。(pp162-163）

48. The power of notation
I asked earlier: Where can we place the number i=√-1 so that its position is appropriate to (and explains its connection to) the transformation 'rotation of the plane by 90 degrees' which we are identifying it? We should aware, when we contemplate this question, that the very framing of it throws us into the late eighteenth or early nineteenth century. We are most emphatically out of the context of sixteenth-century algebra, for our question is one that was not in the vocabulary of Cardano. But however reflective we are about these matters, it seems tricky, if not impossible, to deal with early mathematics (or with any mathematics, FOR THAT MATTER) without helping it along by asking questions about it that extend its frame, even though they may be, in the case of early mathematics, thoroughly anachronistic.

原書では、' '内はイタリック、for that matterは小文字でした。

半分くらいしか理解できずに読み進めているのですが、ここで報告することができたので、よしとしましょう。