How can I find out

If the dumb thoughts I have are because of my mental disease or because I'm a dumb person?
I know I'm in the schizophrenia spectrum. I've had hallucinations and I understand I have a tendency not to raciocinate well because of the fact that I'm in the spectrum. But not every time one has a dumb thought is because he has mental disease or because his brain failed. I don't know if was on the internet looking for ways ro kill someone because I was in a psychotic outbreak or because I'm such a bad person that I considered killing my father. I don't know if the fact that I was in doubt if men are inferior to women is because I have some kind of mental disease or because I'm really dumb. How is someone going to be interested in me, if there is no way to find out if I commited these mistakes because I have a bad personality? I don't understand how someone can be interested in me. If people could be sure that all my mistakes are made because of a mental disease, then I could not be considered guilty. But we cannot say that I'm not guilty or not dumb.
I don't wanna date someone who thinks thinking of killing it's acceptable or that we can forgive this. This cannot be forgiven.

I guess I'll just accept I have some really dumb thoughts sometimes and move on with my life.

Welcome to the forums. If you 'know that you are on the schizophrenia spectrum or know that you have some kind of mental disease', what is your actual diagnosis and are you on any meds or actively attending therapy for it?
I'm only asking because I don't know your situation.

Thoughts by themselves aren't 'dumb' or 'smart', they are just thoughts. Like feelings, they are just there. Acting upon these thoughts and feelings can be a whole other realm though, with good or bad or mixed results.

Wanting to kill dad and the anger behind that sounds familiar to me, as we have that in our own family with my sister. She drinks and won't get help for it (yet).

As to your very good topic question "How can I find out?", we would need more details to offer suggestions. Be aware that we are no substitute for professional therapy and treatment. We are a collection of peer-support. Many of us have gone through what you are thinking now.

Many of us have found things that helped. Talking about it may help find solutions and finding solutions may offer relief. Sharing your burden with another soul may help lighten your own burden.

Best of luck to you.

My diagnosis is schizophrenia and I'm taking meds. But I'm not sure about this diagnosis.
I was thinking he wanted to violate me. So I wanted to kill him as a way of protecting myself. I went on the internet and looked for ways of killing someone *mod edit*, and I remember I was imagining myself killing him this way. I also went to another site and I think I remember myself thinking "I'm going to plan his murder". But I can't even make my bed, I would never be able to plan someone's murder, you know? It takes a lot of effort. And now I don't want to kill him anymore. I was very angry and irritated that day and I think the reason I act like this sometimes is because I believe I'm a bad person.
And the reason I thought men were inferior to women is because for years I didn't have relationships with people. I had a supposed friend who supposably liked me (even though she did something that made me feel upset and now she seems not to like me) when I was 5-8 years old. So if I never had a good relationship with anyone, how am I going to learn about how relationships work, if people are supposed to treat each other equally? Because what I most saw in my life was people treating others differently (including me).

I have felt this way only when completely psychotic. I highly recommend you see your doctor about this as to me, it only went away when I got meds at a psych ward. These to me, are not thoughts that you should have on a daily basis. And I am not judging you, I've had thoughts such as these, just somewhat differently. Let us know what your doctor tells you.