He was complaining (he often does – he’s a moody, introspective kind of guy) about the tendency for business writers to offer one-dimensional arguments.

"I’ve been telling you people for years," he wrote, "that you can make your writing more persuasive by using a combination of rhetorical modes."

I hate it when he uses big words like that. Normally I would have stopped reading right then, but I was having a slow morning – it was one of those splendid Minnesota spring days when the phone doesn’t ring for hours on end because everyone is outside playing hooky – so I read on.

"Look," he wrote. "Remember one thing: People are complex. Human beings are rational, emotional, spiritual creatures. If you want to change their opinion about something or get them to accept your point of view, you need to appeal to them on three levels: their minds, their hearts, and their souls."

As usual, my friend was being a little abstract, so I replied: "Sounds fine, Ari. But what do you mean by ‘rhetorical modes’? How can today’s business writers apply your advice? Would appreciate some specific examples. Doc."

The next day I found this message in my incoming mail:

"First, some definitions. ‘Rhetoric’ is the art of persuasion. Persuasion comes in three basic modes or types: appeals to reason (logos), appeals to emotion (pathos), and appeals to ethics (ethos).

"Logical appeals rely on evidence, research, examples, and data to convince the reader of the truth or validity of an argument. They invite a reasoned response and are usually most effective when the reader is expected to disagree with what is being asserted.

"Emotional appeals attempt to arouse the feelings, instincts, or biases of the reader. Common in advertising and fund-raising letters, emotional appeals often rely on what Herschell Gordon Lewis calls the ‘five great motivators’: fear, exclusivity, guilt, greed, and anger. Emotional appeals are generally most effective when the reader is expected to agree with the argument.

"Ethical appeals rely on the reader’s sense of right and wrong. As Arthur Biddle points out in Writer To Writer, they depend on the writer’s credibility and reputation ‘as a reliable, qualified, experienced, well-informed, and knowledgeable person whose opinions . . . are believable because they are ethically sound.’ In other words, with ethical appeals, the audience is moved not only by what is said but by who is saying it.

"Now, here’s an example of how business writers could construct more persuasive arguments if they used a combination of all three rhetorical modes.

"Our school’s central administration is proposing another cut in our department’s supply budget. ‘None of the other philosophers have new computers,’ they say, ‘so why should you?’

"Now, I could protest on the grounds that a new computer could be purchased (with an educational discount) for only $1,500, and that a new computer would increase my productivity by 5%, and that 5% of my annual salary of $60,000 is $3,000, which amounts to a net savings of $1,500 (logos).

"Or I could argue yet another cut in my supply budget would so thoroughly demoralize me that I might resign my position and start a competing school of philosophy across the river (pathos).

"Or I could appeal to central administration’s sense of fairness by pointing out that the faculty in the school of business got new computers last year and that the humanities faculty always comes last in appropriations (ethos).

"But my most persuasive argument would combine all three appeals."