Enthymemes are the sort of partial and fragmentary reasoning that we find all around us. Often they arise as a short, single sentence that immediately exerts a persuasive force. Often they arrive wrapped in a story or a description.
The purpose of an enthymeme is to let us off the hook, to allow us to circumvent the need for thinking. If a syllogism makes a point in the course of three statements, the enthymeme will make that same point with only two statements, or only one, and leave the remainder of the syllogism implicit.
Let’s take an example. “Wow. The new budget focuses a lot on climate change.” Depending on whose mouth this statement is found, and before what audience, the statement will imply a second statement immediately behind it, either “and therefore the new budget is bogus” or “and therefore the new budget is encouraging to see.” But to reach either conclusion, a third statement, an intermediate one bridging from the first to the second, will also be necessary. “Whatever focuses a lot on climate change as a problem is encouraging to see / is bogus.”
The explicit statement might be unquestionable, might be objective and provable, and since nothing else is said the reasoning itself may seem equally ironclad. “They just said it focused on climate change, which is obviously true. Where’s the problem?” Even if the conclusion is made explicit, the enthymeme might appear very strong, at least to someone who wants to agree with it, since the conclusion seems to be based entirely and directly upon a statement that is firmly rooted in demonstrable reality. It’s only once the third statement is brought to light, the one most deeply concealed, that we can see more clearly how flimsy the argumentation is in itself and how much supplemental argumentation would be necessary to make the argument convincing.
In real life, syllogisms very rarely show up in their mature, elaborated, three-step formulation. Enthymemes are the medium of choice (or more frequently, are the medium of thoughtless resignation). But behind every enthymeme, the syllogism lurks, usually not difficult to find once we know how, and often revealing problems in an argument that are easily skated past when the syllogism is left partly implicit.
The fact that an argument appears in the form of an enthymeme is no disproof of it. Arguments that are perfectly true and perfectly reasonable can be communicated by way of enthymeme.
For a person properly educated, though, an enthymeme is a signal to pause and think, a reminder to resist (at least momentarily) the impulse to give assent to an argument. Enthymemes can conceal major problems in a line of reasoning. When listening to a weighty argument, it is prudent to agree to a point only after having searched out the hidden premises and weighed their value. To do otherwise just makes us the willing tools of others, the obedient dupes of whoever talks first or loudest.