Question: who argued that as a philosopher he was committed to radical skepticism

title: Philosophical skepticism
text: `` The Debate on the Joy of Fish '' ( 知 鱼 之 乐 ) : In this anecdote , Zhuang Zhou argued with his fellow philosopher Hui Shi on if they knew the fish in the pond was happy or not , and Zhuang Zhou said the famous sentence that `` You are not I . How do you know that I do not know that the fish are happy ? '' ( Autumn Floods 秋水 篇 , Zhuangzi ) `` The Butterfly of the Dream '' ( 周公 梦 蝶 ) : The paradox of `` Butterfly Dream '' described Zhuang Zhou 's confusion after dreaming himself to be a butterfly : `` But he did n't know if he was Zhuang Zhou who had dreamt he was a butterfly , or a butterfly dreaming that he was Zhuang Zhou . '' ( Discussion on Making All Things Equal 齐 物 篇 , Zhuangzi )