My good friend and pastor, Jeff Miller, started a sermon series yesterday on the book of Ephesians. While covering issues that prepared the congregation for his forthcoming exposition over the next several weeks, he gave a picture-perfect example of how to avoid the word-concept fallacy. In a nutshell, the word-concept fallacy is the exegetical mistake of assuming that a concept is present in a text only when particular words are also present. Essentially this fallacy equates concepts with particular words, when in fact they are much broader. For example, think of all the words you could use to talk about marriage without actually using the word itself: man, woman, husband, wife, covenant, divorce, family, wedding, etc. The exegete needs to recognize that words may signal that a concept is in play without actually using the word that most strictly signifies that concept.
The way Jeff demonstrated this was spot on and easy to follow. First he emphasized that a major theme of the book was unity. The problem is that the word "unity" only shows up twice in the book (the Greek word ἑνότης occurs in 4:3, 13). How can it then be a major theme? If you tripped over the word-concept fallacy, you would say that it isn't a major theme for that very reason. But if you navigate this land mine properly, you realize that the concept of unity is referenced by a whole host of other words which point back to it. Jeff then proceeded to show these: in Christ, peace, love, etc. So even though the word "unity" is not prominent, the concept is and can be thought of as a major theme for the book.