user-1: I am often harsh, though I don't think hurtful, in speech about others, because of my schizophrenia and psychosis. I often believe they are up to no good and need to be stopped verbally from doing that.
Can you advise on how best to work on that? I have not taken any precept that prohibits it, but then it is my default bad karma.

user24191: 
Can you advise on how best to work on that?

I think., you have stated the reason yourself as below.

I have not taken any precept that prohibits it,

Taking the precept is the best option that I can see.

but then it is my default bad karma.

Intention (action) is not a karma vipaka (result of past karma).
Intention is karma that gives a future vipaka.
Taking or not taking the precept is not a karma vipaka.
Taking the precept is a wholesome karma that gives beneficial results in the future.
Not taking the precept is an unwholesome karma that gives harmful results in the future.

I am often harsh, though I don't think hurtful, in speech about others, because of my schizophrenia and psychosis.

I guess Metta meditation would be a good remedy.

I often believe they are up to no good and need to be stopped verbally from doing that.

The Buddhist teaching is the world is not under the Authority of any one. Everything in the world is Anatta (devoid of hegemony). We can't control the world or change the world according to our wish. World is owned by causality. World functions according to the Dhamma-formulas.
Understanding the nature of the world makes our mind to work according to the Dhamma-formulas. Then we would not try to change the people in unskillful way. We can learn skillful ways of advising as well.
If you could read Nandivisala Jataka, then you would find the teachings on the drawbacks of harsh speech and obvious benefits of friendly speech.

-1: <p>I am often harsh, though I don't think hurtful, in speech about others, because of my schizophrenia and psychosis. I often believe they are up to no good and need to be stopped verbally from doing that.</p>
<p>Can you advise on how best to work on that? I have not taken any precept that prohibits it, but then it is my default bad karma.</p>
 24191: <blockquote>
<p>Can you advise on how best to work on that?</p>
</blockquote>
<p>I think., you have stated the reason yourself as below.</p>
<blockquote>
<p>I have not taken any precept that prohibits it,</p>
</blockquote>
<p>Taking the precept is the best option that I can see.</p>
<blockquote>
<p>but then it is my default bad karma.</p>
</blockquote>
<p>Intention (action) is not a karma vipaka (result of past karma).
Intention is karma that gives a future vipaka.
Taking or not taking the precept is not a karma vipaka.
Taking the precept is a wholesome karma that gives beneficial results in the future.
Not taking the precept is an unwholesome karma that gives harmful results in the future.</p>
<blockquote>
<p>I am often harsh, though I don't think hurtful, in speech about others, because of my schizophrenia and psychosis.</p>
</blockquote>
<p>I guess Metta meditation would be a good remedy.</p>
<blockquote>
<p>I often believe they are up to no good and need to be stopped verbally from doing that.</p>
</blockquote>
<p>The Buddhist teaching is the world is not under the Authority of any one. Everything in the world is Anatta (devoid of hegemony). We can't control the world or change the world according to our wish. World is owned by causality. World functions according to the Dhamma-formulas.</p>
<p>Understanding the nature of the world makes our mind to work according to the Dhamma-formulas. Then we would not try to change the people in unskillful way. We can learn skillful ways of advising as well.</p>
<p>If you could read <strong>Nandivisala Jataka</strong>, then you would find the teachings on the drawbacks of harsh speech and obvious benefits of friendly speech.</p>
