We all operate with abstractions and simplifications - because it's impractical (and actually impossible given the complexity of the world) to process end evaluate every single detail.
Dealing with contradictions in our own beliefs (paradoxes) is a part of life. The rational approach is to accept that and "fuse" those beliefs carefully, not (a) accept one and reject the others or (b) avoid the topic entirely.
The rational approach is to acknowledge that you do not have sufficient information to proceed, or acknowledge the various assumptions (better word than “belief) that you are using.
If you are using contradicting assumptions, then you should probably check to see if you are doing so because you want the conclusion that you are getting from the assumption.
We make decisions based on imperfect information and conflicting values every day. We generally can’t wait until we have sufficient information to proceed.
Dealing with contradictions in our own beliefs (paradoxes) is a part of life. The rational approach is to accept that and "fuse" those beliefs carefully, not (a) accept one and reject the others or (b) avoid the topic entirely.