Reason is not exclusive wishful thinking. That's why libertarians and some classical liberals pushed natural law so much
Discussion
Reasoning isn’t belief
The trick is that reason is mostly unknown. We deal everyday only with poor microscopic nuggets of reason that almost never complete the real landscape of our situation in the course of our lives.
Iusnaturalists including Aquinas say that natural rights are like an onion. You keep delving inside and you find more and more