Because advertising grew up in a world where media was scarce, we got used to compression and density being key communication skills.
A proposition is the densest possible articulation, the work of a planner that has compressed everything necessary down into the smallest possible space. [Convergent]
And a tagline opens that meaning back up again, attempts to express as much as possible, to as many people as possible, in the most memorable textual unit. [Divergent]
Which is why advertising has long thrived on paronomasia - or PUNS - because leveraging phonic ambiguities allows you to say two different things at the same time, and when people decode it, it feels satisfying.
[Apparently in China, because of the way language is constructed, layering meaning is far more complex, so a tag line can have 10 meanings layered into it.]
Of late, I've noticed a specific form emerging: PUNctuation - that is, using punctuation to create multiple meanings.
Sony's new line is: make.believe - they explain why on their site makedotbelieve.
But then I started to see it everywhere:
And this morning I got to meet the CEO of AOL Tim Armstrong at a lovely breakfast thrown by the awesome people at Wolff Ollins [thanks dudes!] and Rosie pointed out to me that they are at it as well:
UPDATE: a submission from Dave:
and one from Sarah: