How to Overcome a Bear Case to Buy a Stock

Do you need to have a theory as to why it's undervalued? Or do you just accept that it's undervalue and then exploit it from that basis? The reason I ask is because a lot of the time we're fishing in the same pond, I suspect. If you could see me, I suspect you'd say only our mothers could tell us apart. For me, the issue is you can waste a lot of time trying to find a narrative that explains why stuff is cheap. You'll never know. Not even Goldman Sachs will know that.