People talk within themselves throughout the waking time which is known as internal conversation, internal monologue, self-talk, inner speech, inner discourse, or internal discourse.
It is quite natural and normal. However, some people argue in their heads which leads to internal conflict, anxiety, and depression.
Most challenges in individuals arise due to the arguments within their minds. When people feed their minds with negative information they evolve as negative individuals whereas when people feed their minds with positive information they evolve as positive individuals.
When you argue in your head, you poison your mind and waste your precious time. It may have adverse effects on the people around you.