Who owns How?

No, that’s not a line from a Dr. Seuss book or an Abbott and Costello routine.

It’s the question at the center of a bitter legal battle pitting a best-selling author and management guru against America’s largest Greek yogurt manufacturer.

The author, Dov Seidman, is in the business of helping companies create more ethical cultures. He has distilled that business to a single three-letter word: how. President Bill Clinton wrote the foreword to his book, “How: Why How We Do Anything Means Everything.” (“This is a HOW book, not a how-to book,” it begins.)

Enter the yogurt maker, Chobani. Founded in 2005 by a Turkish immigrant who was turned off by the runny texture of American yogurt, Chobani recently got into the “How” business, too. The company is in the midst of an ambitious brand campaign intended to highlight the quality of its yogurt and the way it is made, including a straining process that makes it extra dense. It is built around the phrase “How Matters.”

To Mr. Seidman, who also uses “How Matters” in some of his materials, the campaign represents a frontal assault on the brand that his company, LRN, has spent 10 years building. Chobani has stolen his “How,” he says, and he wants it back. He is suing the company and its advertising agency, Droga5, asking a court to order Chobani to halt the campaign because it represents an infringement on his trademark for the word how.