וַיִּגַּשׁ יַעֲקֹב אֶל־יִצְחָק אָבִיו וַיְמֻשֵּׁהוּ וַיֹּאמֶר הַקֹּל קוֹל יַעֲקֹב וְהַיָּדַיִם יְדֵי עֵשָׂו׃ - So Jacob drew close to his father Isaac, who felt him and wondered. “The voice is the voice of Jacob, yet the hands are the hands of Esau.” Genesis.27.22
Apparently, Isaac was puzzled with the choice - whether to believe his senses (touch and smell) or to believe his feelings and logic (Yaakov's language). And he chose to stick with his physical senses and think it's Esov.
I would expect a Tzadik to look at the essence of a person and not the outer form as the Mishnah in Avos: Don't look at a jar but its content.
Why did Itzhak trust his senses over his feeling?