Without facts,we can't form a worthwhile opinion for we need to have factua

Without facts,we can't form a worthwhile opinion for we need to have factua
Without facts,we can't form a worthwhile opinion forwe need to have factual knowledge upon which to base our thinking.
看不懂这这句upon which to base our thinking
base 以...做基础，以我们的思想做基础？翻译过来不对头
base upon 根据；以……基础
这句可以怎么改