A ceremonial argument is a speech given in social functions in respect of a particular current event. This speech usually emphasizes praise or blame of a specific idea, person or trend. It mostly focuses on the present affairs of the people.
A ceremonial argument, or an epideictic argument, is borrowed from the Greek culture and simply means "fit for display." Basically, it implies that the speech focuses on displaying the actual truth behind something or someone with regard to a given social gathering. For instance, a eulogy is a perfect example of a ceremonial argument. It praises the life of the deceased or exposes it in a bad light.