How do you convince someone that what they know to be true isn't true?

If someone truly believes with all of their heart that the world is flat how do you convince them otherwise?

If someone believes that they are worthless than the piece of crap you just stepped in how do you convince them otherwise? What's the point in positive affirmation if you don't believe what you're saying? What do you do if that "inner" voice just laughs and says "No you're not you worthless piece of crap"?
What's the point of therapy if it doesn't work and they don't listen?

Are you talking about yourself or trying to convince some else? My impulse is to give rational explanations or credible evidence. If someone doesn't believe that the world is round, and the proof is something you cannot see with your own eyes, I would say we need to have faith in the people who tell us the world is round. Teachers and scientists are people who proved their reliability by helping society in ways that we can see on a daily basis, so we should trust them when they say the world is round because we have faith in their competence and honesty.

Self worth is also something you cannot really see with your own eyes. So, likewise, you need to have faith in the opinions of people who have earned your trust. Such people could include therapists, teachers, friends, and anyone you know to be honest and intelligent.

Sometimes, you can trust the evidence of your own experience and knowledge. My family often tried to convince me I was worthless and stupid. I would say they were wrong because I got good grades so I was obviously not stupid. Worth is a little harder to define than intellect, but I used my family's determination to control me to mean I had some value they wanted to exploit.

If you have doubts about your worth, consider if there has been someone who wants to stay in your life whether or not you want them to. Usually, such a person will try to convince you that you are worthless because they are afraid of losing you. Also consider what abilities and personality traits you have that people want or benefit from. Worth can be defined more materially as having a positive impact on society either by doing good or doing no harm.

If you are talking about convincing someone else of something they refuse to believe, you might have to accept that you cannot change their thinking. Sometimes, insecurities make people afraid to look at a truth that is looming over them. Sometimes they simply do not have the mental ability to understand something that you know.

I hope that helps.

I don't know the answer. But I don't think we should judge if we have worth by anyone else's opinions either. I think even the smallest creatures have worth. Even so called stupid or mentally handicapped people have worth. You and everyone is here for a reason. If we can't find it in ourselves we can't love anyone else either. I didn't and still don't see hardly anyone in my life saying I have value to them. I see a selfish and insane society that is driven by material longings (of course not EVERY HUMAN,) but I think it's up to ourselves to find and do things by ourselves to find our values and what we are here for.

I read somewhere that conspiracy-like theories like flat earthers have similar thinking to people in a cult. Almost like they are brain washed and refuse to see any truth. I do not know how to circumvent that. Politics is another area where this can happen. I just choose to love and be friends with people because I connect with them and leave off limits topics aside. I may try once to convince someone that say.. the moon landing is real but if it doesnt work its a waste of my time.

Positive-affirmations have never worked for me. They apparently work for enough people that the proponents of some varieties of cognitive-behavioral therapy strongly promote positive affirmations as a way to influence one's moods and emotions.

My personal experience with attempts at positive affirmation, forced "positive self-talk," is similar to yours, Twitch99.

In my case, the less I think and focus on myself the better.

Good to know I'm not the only 1. But when you don't focus on yourself do you have people saying you need to think about yourself?

Of course!

But, I am mostly a recluse - I don't have that many "real-life" interactions, and my moods+meds blunt the impact of what others advise.

Positive affirmation and supports may seem useless to someone who is struggling REALLY BADLY with him/herself, although I don't think they REALLY ARE useless, but they certainly may seem that way. I certainly believe that Love and Self-Acceptance must come from withing ourselves FIRST. Other people can help but they can't do it FOR us. It is hard when we ourselves don't believe we have ANY worth... we are our biggest enemies! I think it's important to go to the root cause of WHY we feel the way we do, something that can be done especially well in Therapy. But of course it takes a little bit of Courage and a little bit of Hope. Hope that there IS abetter Future waiting for You and Your Family... I am not sure how things are going with your therapist, but please give it a try. See another one if the one you're currently seeing isn't helping you of making you feel too comfortable. I know it's hard..... but please, take this opportunity. You can change things..... YOU CAN DO THIS AND YOU KNOW THAT! THAT'S ABSOLUTELY AND UNDENIABLY TRUE AND YOU ALSO KNOW THAT'S ABSOLUTE AND UNDENIABLY TRUE AS WELL EVEN IF IT'S DEEP DOWN INSIDE YOU! Sending many safe, warm hugs to BOTH you, @Twitch99, your Family, your Friends, your Wife, your Therapist and ALL of your Loved Ones! KEEP FIGHTING AND KEEP ROCKING NO MATTER WHAT HAPPENS, OK? Please feel free to PM me ANYTIME when you want to and need to! I am SURE plenty of others will BE REALLY, REALLY, REALLY, REALLY, REALLY GLAD AND REALLY, REALLY, REALLY, REALLY, REALLY HAPPY TO HELP YOU OUT AS WELL! KEEP FIGHTING AND KEEP ROCKING NO MATTER WHAT HAPPENS!