A “deductive” method of studying the Bible involves picking a certain topic and then going through the Bible and finding passages that support the topic. This is related to the “topical approach” to Bible study.
Another form of Bible study, in contrast to the deductive method, is the “inductive” method. Using an inductive method, students take a verse or a passage, break it down, and examine its details to draw out the meaning.
There are two kinds of reasoning: deductive and inductive. Deductive reasoning moves from the general to the specifics. Inductive reasoning moves the other way, from the specific to the general.
Deductive reasoning starts with a general or universal statement and then goes looking for details to support it in order to make a specific application. So, someone might say, “All men are mortal. Bob is a man. Therefore, Bob is mortal.” The general statement “All men are mortal” is the starting point, and deductive reasoning leads him to conclude, specifically, that Bob is mortal. If the general starting statement and the second statement are true, then the specific application is also true. If either is false, then the specific application is invalid.
Inductive reasoning starts with the details and moves to a general conclusion. To illustrate, suppose a man has a bag full of objects and he pulls out one red stone from the bag. The next thing he pulls out is also a red stone, and so on. After four or five times of extracting a red stone, the man concludes that the bag is full of red stones. He has used induction, taking the specific detail of “a red stone” and applying it to the general case: “All stones in the bag are red.”
Deductive Bible study, then, is simply taking a general statement and then going to Scripture to find details that support (or disprove) it. Inductive Bible study does the opposite. It starts with the details of Scripture and then builds a general or universal statement based on those details.
An example of deductive Bible study might be to start with the general statement, “Sin leads to death.” The student of the Bible must then go to Scripture to find passages that support that statement. He might cite Romans 5:12, Romans 6:23, Ezekiel 18:20, and Jeremiah 31:30. If he finds that Scripture does indeed support his premise that sin leads to death, he can then make a more specific application: we are all in danger of death, because we are all sinners (Romans 3:23).
A weakness of the deductive method of Bible study has already been mentioned: if we start with a false premise, then we will not arrive at a proper conclusion. For example, we might start with the general statement, “All angels have wings.” We might even find a passage or two in Scripture that mentions angels’ wings, such as Isaiah 6:2. But if our conclusion is “Michael has wings, because Michael is an angel,” then we are on shaky ground. The Bible mentions Michael the archangel (Jude 1:9), but it never mentions Michael’s wings. In fact, the Bible never says that all angelic beings have wings; some angels do, but perhaps not all of them. Deductive Bible study, to be beneficial, must begin with a universal truth rooted in Scripture. If we begin with conjecture or our own ideas, then we end up with a possible falsehood.
When misused, deductive Bible study takes on aspects of a priori reasoning and biblical eisegesis. In other words, deductive Bible study can facilitate a person’s drawing a conclusion before the fact (a priori) of studying the biblical text or reading into it (eisegesis) his own meaning. Obviously, such a practice is dangerous and irresponsible because the conclusions that one might draw are often premature, subjective, and false.
When used properly, deductive Bible study is akin to topical Bible study. We take a general topic, such as the love of God, and find all that the Bible (or a book of the Bible) says on that subject. From those gathered details, we can draw a conclusion. In this way, deductive Bible study is a useful tool in studying broad topics of Scripture.