Our horizons are bounded. The thoughts and opinions we can have are limited by our cultural experience (e.g. socially accepted norms). Our confidence in our beliefs is bolstered by the fact that we can only operate inside our tiny little box, which makes everything in the box so familiar and comfy and, you know, "obviously true".
However, to make good decisions in life, we must accumulate much "experience" to guide us. That "data" comes in the form of a diverse array of opinions and beliefs, which may not agree with each other. We must expand our shoebox of a mind to a warehouse of different perspectives which allow us to appreciate things and happenings more completely. This will aid our decision-making process by allowing us to evaluate the consequences of choices more accurately.