The Litany of Tarski is a template to remind oneself that beliefs should stem from reality, from what actually is, as opposed to what we want, or what would be convenient. For any statement X, the litany takes the form “If X, I desire to believe that X”.
Quoting The Meditation on Curiosity:
If the box contains a diamond,
I desire to believe that the box contains a diamond;
If the box does not contain a diamond,
I desire to believe that the box does not contain a diamond;
Let me not become attached to beliefs I may not want.
Why truth? And… — You have an instrumental motive to care about the truth of your beliefs about anything you care about.
A Fable of Science and Politics—characters discover the color of the sky, with political implications.