In this great article, Sagi Haviv discusses principles of identity design as they manifest in trademarks created by his firm, Chermayeff & Geismar & Haviv. Here’s an excerpt:
Recently a big international bank came to us asking that we design a symbol for them, as Tom Geismar had done many years before for The Chase Manhattan Bank. For over a decade, this international bank had been using a wordmark for their short four-letter name. We advised that they did not need a symbol and turned down the job.
Creating a symbol can be a great design exercise, but we try to be very disciplined about only developing a symbol when there is a compelling strategic reason to do so. This is because visual identities work through familiarity, so any new visual element has to be learned first in order to be established. Using a symbol as part of the logo means that there is an additional element that has to be learned. We find that people are generally willing to learn as little as possible.
There are, of course, good reasons to create a symbol as part of an identity program. For example, if you have a long name, like in the case of The Chase Manhattan Bank (now simply “Chase”), a symbol may help tie it together as a unit and add visual impact. […]
But absent a good reason for a symbol, it is always a better idea to start with putting the emphasis on the name and trying to find a simple, focused way—a change of color, an unusual arrangement of letters, a graphic accent or even just a unique lettering style—to make it memorable.