Propagandists know the value of a slogan. It is simple, catchy, and easily remembered. An involved train of thought is hard to follow. A series of arguments is hard to remember. A slogan makes thinking unnecessary. It oversimplifies by reducing a chain of arguments to a few words.
Slogans play an important part in politics and advertising. When you hear a slogan, remember that it does not tell a complete story. It is a device to capture your attention and memory.
Chapter 23 Language and Logic, in Warriner's English Grammar and Composition Revised Edition, Complete Course, John E. Warriner and Francis Griffith, 1965