抑々 (そもそも) is a jukujikun reading, where the kanji 抑 (normally ヨク) are read together as そもそも. Misreadings like よくよく apply the individual On'yomi, which is incorrect for this adverb. It means "in the first place," "to begin with," or "originally," introducing a fundamental point.

抑々 (そもそも) は、漢字の並びから推測できない特別な読み方（熟字訓）です。個々の漢字の音読みで「よくよく」と読むのは誤りです。「最初に」「本来」「一体」といった意味で、物事の根源を問う際に使われます。