One of the more common mistakes in persuasion (intentional interpersonal influence) is assuming that people know much more than they actually know. This is known as the COIK (Clear Only If Known) fallacy. As persuaders (2 Cor. 5:11) we need to be careful lest we fall victim to this fallacy.

Many of us have, no doubt, asked directions only to be told after some very ambiguous directions, "You can't miss it." What is really meant by "You can't miss it" is "If I were going there, I could not miss it." COIK.

Preachers are often victims of the COIK fallacy. We assume that our hearers know what we mean when we should be much more explicit. Consider the woman who was overheard, after hearing a lesson on the conversion of Saul of Tarsus, saying, "From what that preacher said someone might get the idea that Saul and Paul were the same person." Well has it been said, "Never underestimate the ignorance of your audience."

The problem is complicated by well meaning brethren who compliment our poor lessons. The saint, with greater knowledge, mentally fills in our omissions and all the while the alien sinner is left completely in the dark. In our teaching-preaching the gospel of Christ, it is Clear only if known.

Truth Magazine XIX: 12, p. 181
January 30, 1975