What semantic notions underlie 駁 (to rebut) with 馬 (horses) and/or 爻 (I Ching's hexagrams)? I'm trying to understand the etymology for definition 3 (to rebut) below in 駁 - Wiktionary. Yellowbridge:


Han character
駁 (radical 187, 馬+4, 14 strokes, cangjie input 尸火大大 (SFKK), four-corner 74340, composition ⿰馬爻)
豹 (OC *preːwɢs, “leopard”) is its exopassive derivative, literally meaning, &quot;the spotted one&quot;.
Definitions

(of a horse's fur) variegated
mixed; heterogenous
to refute; to rebut
to transport by barge
barge
suddenly


I don't understand how 馬 or definition 1 (variegated horse's fur) relates to definition 3. So I looked up 爻 - Wiktionary, but I also don't understand how the I Ching's hexagram relates. I'm too addled to continue!


a figure composed of six stacked horizontal lines; a hexagram of the I Ching
Two notes:


The original meaning of 「爻」 is criss-cross patterns, rather than I-Ching hexagrams;
「爻」 provides a phonetic hint to 「駁」.




「駁」 (Baxter-Sagart OC: /*pˤrawk/, patterend/variegated horse fur) is composed of semantic 「馬」 (horse) and phonetic 「爻」 (/*N-kˤraw/). 「爻」 (criss-cross patterns) simultaneously provides a meaning hint.

The semantic extension is as follows:


Variegated horse fur
Impure/mixed colours and patterns (looking like a jumbled mess)
To distinguish, rectify (e.g. in the process of sorting out a jumbled mess, correcting what is chaotic/wrong)
To rebut (e.g. to refute falsehoods, denounce wrongdoing)




References:


漢語多功能字庫
《漢語大詞典》