Sun Tzu stated that, "Those skilled in war cultivate the Tao and preserve the laws and are therefore able to formulate victorious policies." The Tao, or "The Way", was created by the ancient Chinese philosopher Lao Tzu and has had a major impact on China's culture.
In Taoist philosophy something, say a vase, can be prized not only for it's beauty, but also for its "emptiness". For it is not the vase's beautiful outside but the empty inside that provides value by allowing itself to be filled up with water, wine or another liquid. Advertising slogans and tag lines perform the same function; as stated they communicate not only something about the company or product itself (e.g. Ford, Where Quality is Job One) but also subtly portray other companies in a poorer light with their unsaid message. In the Ford example above, the implication is that other companies don't focus on quality as much; therefore, their products may have higher failures rates. So a slogan or tag line needs to communicate both directly (the stated message) and indirectly (the unstated message) to customers.
Slogans such as Campbell's "Hmm, Hmm, good" sends a clear positive message about the product while also placing in the consumer's mind a question about the competitor's product. This approach effectively makes use of both the form and the emptiness. As Sun Tzu said, "Therefore, the skillful commander takes up a position in which he cannot be defeated and misses no opportunity to master his enemy."
