begging the question
Assuming, in the premises, the very conclusion you are trying to prove.
An argument begs the question when one of its premises, perhaps reworded, already asserts the conclusion or depends on it being true. Such arguments can be valid, but they give no support to anyone who doubts the conclusion. The phrase does not mean "raises the question."
Examples
"This website is trustworthy because it says so on its About page."
See also