What makes this an argument and not just any old statement?

Here is an example of an argument: Uniforms should be mandatory in public schools.
What makes this an argument and not just any old statement? Verbs like “should be” and the word “mandatory” are a good start, right? There is no doubt that this claim is taking a stance, a stand, a position.
Try it for yourself— Write making an argument about anything discussed in Jordan’s Report from the Bahamas.