Question: "What is synthetic parallelism in Hebrew poetry?"
Answer: Many books of the Old Testament were written as poetry. The Wisdom books of Job, Psalms, Proverbs, Ecclesiastes, and Song of Solomon are wholly poetic. The Major and Minor Prophets were also written largely in poetic form. Because there’s so much poetry in the Hebrew Bible, it’s fitting to familiarize ourselves with the basics of Hebrew poetry. What is it that makes a Hebrew poem poetic? In a word, parallelism.
In our language, parallelism is the repetition of certain sentence parts for rhetorical effect. English uses parallelism quite often, as in the proverb “like father, like son.” A. A. Milne’s words, “You are braver than you believe, stronger than you seem, and smarter than you think,” also exhibit parallelism in their three clauses. In the Hebrew language of the Old Testament, parallelism goes beyond simple grammatical form to include repetition of thought.
Take two lines of poetry. In synonymous parallelism, the idea of the second line is a restatement of the idea of the first line (see Proverbs 18:7). In antithetical parallelism, the idea of the second line is the opposite of the idea in the first line (see Proverbs 18:23). In synthetic parallelism, which is not really parallelism at all, related thoughts are brought together to emphasize similarities, contrasts, or other correlations.
One type of synthetic parallelism simply classifies certain behaviors or traits. For example, Proverbs 21:4 classifies three characteristics of a wicked heart:
“Haughty eyes and a proud heart,
the lamp of the wicked, are sin!”
Another type of synthetic parallelism presents an action side by side with another action of greater (or lesser) consequence. Proverbs 21:27 is an example:
“The sacrifice of the wicked is detestable –
how much more so when brought with evil intent!”
This verse takes one sinful action—offering a sacrifice with a wicked heart—and compares it to an even greater sin—offering the sacrifice for the express purpose of sinning! It’s an argument from “less than” to “greater than.”
Another type of synthetic parallelism involves the formula “better this than that.” For example, consider Ecclesiastes 7:5:
“It is better to heed a wise man’s rebuke
than to listen to the song of fools.”
Songs are usually pleasant to hear, and we usually don’t like to be rebuked, but given the choice between a fool’s song and a wise man’s rebuke, choose the rebuke every time. Proper guidance is valuable; no amount of entertainment can compensate for bad advice.
Because synthetic parallelism is such a broad category, there are many other types that could be identified. Basically, when the structure of the poetry is not synonymous or antithetical, then it could be considered synthetic.