Though perhaps it's not a good idea to introduce a fourth persuasive strategy to the balanced "magic of three" formed by ethos, logos, and pathos, introduce it we must. Lesser known than credibility, logic, and emotion as ways of persuading others to accept an argument, this fourth may be something many of us know instinctively. It is kairos—time—the kind of time captured in Shakespeare's King Lear: "Ripeness is all."

Kairos comes to rhetoric and other fields from the ancient Greeks. While it is not exactly the opposite of chronos, another ancient Greek word for time, kairos does designate something quite different. Chronos—from which we derive such words as chronology and anachronistic—refers to sequential time, the ticking away of seconds on a clock.

But as communicators, we also need kairos, a word that refers to non-sequential time, to the right or most opportune moment, to the moment most favorable. Kairos also applies to lengths of time greater than a moment—to a period of time such as our current age of robots or to a societal condition such as homelessness.

A writer or presenter who can identify and use those propitious moments or periods increases the chance that her message will be accepted.

STAY OPEN

Kairos can be used to advise a change or to recommend none at all. If, for example, your message is that a current SOP should be kept as is rather than undergoing a revision that has become popular in your industry, you can take that popularity as your right moment to argue against the change. Your message would be that the revision, no matter how popular, does not suit your company and its unique processes. You would support that message with evidence that shows how the current SOP meets your company's needs or how the revised one would not add any advantage. Or both.

STAY AWARE

Most likely you cannot delay the delivery of a document or presentation until a kairos opportunity arises. But you can remain aware of the winds of change and action whirling around you. Keeping your ear to the ground for trends or issues within your profession, such as new technology or changing compliance rules, is one such way, for it allows you to fit your messages into a wider but current context.

Another way is to increase your sphere of knowledge by becoming more familiar with fields similar or connected to your own; developments gaining strength in one area often pick up other areas along the way. And if you go even wider, you may find in your own country and culture as well as in others some event, principle, or practice that offers the timeliness from which your message can benefit. Look for moments.

STAY ATTUNED

All messages are best constructed with your audience members in mind. It's important to discern their attitudes, beliefs, values, and motives as well as you can and to grasp how these qualities may operate in their understanding of your message. Such knowledge can help you determine how to present your message most effectively, including identifying a potential kairos opportunity.

Kairos straddles all other persuasive strategies and, as Hesiod, a Greek poet thought to have lived around 700 BCE, writes, "Timeliness is best in all matters."

It's hard to argue with that.