It is by universal misunderstanding that all agree. -- Baudelaire
Slogans are motivational devices. Their point is to get you (“people”) to do things or avoid things you would not otherwise -- in someone’s opinion -- do or avoid. Any discomfort or reticence you might feel is to be compensated by your knowledge that you, accepting the slogan, are now part of a group, a member in consensus, a sharer of the faith.
Slogans are often factually false, e.g. “X-Mart: where America shops!” Slogans often promise more than they can deliver, e.g. “Yes, we can!” Their vagueness often makes potential enemies seem like fellow travelers, “A sound economy is our primary consideration.”
But forget about truth, promise and clarity: another point of slogans is to bypass your careful consideration, your judgment, your inquiry, your weighing of options: Don’t ask questions; just do it!
But slogans are often little more than motivational junk food. At first taste, they’re yummy. But any deeper bites and you come up with a strange taste that puts you off: you realize that what you thought was meant by the slogan is something others can’t go for. Slogans provide no lasting sustenance to focused action.
For people who like to get down to the nuts and bolts, the vagueness of slogans makes them practical dead weights. You try to interpret them so as to get something done, and some ideologue quibbles about what the slogan “really means” -- as if their interpretation were the only one possible.
Under these circumstances, slogans become intellectual poison. Their champions try hard to shut down diversity of understanding and force their narrow, self-serving interpretations on everyone.
For references and to examine these issues further, see Slogans in Education (and Politics?)