Circular Argument

What is circular argument?

Systematic Theology by Wayne Grudem gives some example:

pg.78
We believe that Scripture is God's Word because it claims to be that. And we believe its claims because Scripture is God's Word. And we believe that it is God's Word because it claims to be and so forth.

pg.79
My reason is my ultimate authority because it seems reasonable to me to make it so.
I know there can be no ultimate authority because I do not know of any such ultimate authority.

I think these kinda argument might appeal more to the Chelliah brothers.