Of course, by "you" I mean everybody, and by "SO" I mean "very" or "really".
I know better than anybody how crap I am at maths, and don't think this is false modesty because I also know that I'm better at it than most people. Despite my crapness I also know enough about the subject and its history to get a sense of how demanding it is. It's not just about making sure that each step is mathematically correct, but that your problem is posed in a way that makes sense. Even given all the rigour that mathematicians bring and peer review, it isn't uncommon that a paper with errors in it will get published. Andrew Wiles is "famous" for proving Fermat's Last Theorem but it took a long time for people to discover that his initial attempt was incorrect, and it was probably only discovered at all because so many weirdoes were interested enough to check.
My point is that when it comes to actually knowing stuff for sure you can't do better than maths (or logic) but even here it's often less of a sure thing than you'd guess and it's really, really hard. And maths and logic is actually the easiest stuff that we can ever do. In real life we can't pose questions with similar precision and we can't move from one step to the next in the same deductive way, so why should we expect our chains of reasoning to lead to accurate conclusions? Well, we shouldn't. But we are often really confident about our beliefs when it comes to politics or economics or sociology, which are indescribably more difficult and complicated than maths.
If you have an argument that involves a chain of reasoning and on average you're 95% sure that each step is correct, the odds of your argument being right falls below 50% on the thirteenth step.
Or put another way, the odds of you being right declines exponentially with the length of your argument.