The Function of Doubt

What is the purpose of doubt & self-criticism?
It exists, which means it came from somewhere, which means it evolved to serve some sort of purpose...so, what is it?
There are a few things I'm going to hit on here:
Relationship with yourself
Grounding in reality
Overcoming thought distortions
1. Relationship with Yourself
First off, if you don't know already, you are always in a relationship with yourself. can prove it.
You can think about and describe yourself, right? You can judge who you are and what you do. This ability to self-reflect, to be self-aware, to talk about yourself like you would anyone else, proves that there is some third-party observer within us.
Let that sink in.
You are constantly watching your every thought, feeling, and action. This would be like spending every waking moment following someone's instagram and evaluating what you think and feel about where they're doing...sounds exhausting, right? Thankfully, it's automatic. It doesn't take any extra effort because its our own experience.
Now that we've established that...what is your relationship with yourself like? Are you kind, loving, forgiving, understanding, compassionate, encouraging, and accepting? Are you hurtful, invalidating, cold, judgmental, discouraging, and punishing?

Are you your Best Friend or Your Own Worst Enemy?
2. Grounding in Reality
Next up, whether you think you're God's gift to earth, Satan's curse upon the land, or somewhere in between, are you grounded in reality?
Here's where other relationships come into play–and this is a bit of a mindfuck. Yes, we are in a relationship with ourselves; however, we cannot truly see beyond our own experiences. Th