Me: I’m making an assumption
Lee: But that’s an assumption
Me: Yes, I’m assuming that rationality is accounted for by reality
Lee: You are concluding your assumption
Me: It is an assumption, not a conclusion
Lee: But you cannot argue that way
Me: It’s not an argument, I just assume that we can ascertain external reality, you can do no better.
Lee: So what’s your argument?
Yes. Reasoning is fallible, which is consistent with natural development, and not being derived from some ultimate, self sufficient source.
If reason is fallible, then it cannot be trusted absolutely. That is indeed the case, but that does not necessitate it is hopeless. We muddle along as best we can.
Paradoxically, your reasoning exhibits that reason cannot be trusted. You may want, desire, demand, a more foundational assurance, but you can’t always get what you want just because you want it.