Deductive reasoning, or the ability to draw an accurate conclusion based on at least two facts, is a critical thinking skill that many employers seek, but a 2022 Reboot report found that only 39% of eighth grade teachers report emphasizing it in their classrooms. This may explain why one of my ninth grade composition students spent three weeks trying to write a persuasive essay arguing that violent television content does not increase aggressive behavior in children--despite her inability to find any research that supported her thesis. Her search for facts that support a desired conclusion is known as inductive reasoning, and it causes people to disregard important evidence that doesn’t say what they want it to. In contrast, deductive reasoning occurs when one analyzes a set of data to arrive at a conclusion that the data supports. My student might have wanted there to be no correlation between television violence and aggression in children, but in the absence of supporting evidence, her thesis didn’t work.
Deductive reasoning also includes the ability to differentiate between relevant and irrelevant information. Reading comprehension tests assess this ability by asking students to distinguish between a passage’s main idea and its supporting details. Students who skim or read too quickly are apt to get these questions wrong. Teaching students to read more attentively can make a big difference here; my policy is to read aloud any test passage on which a student gets more than 40% wrong because they almost certainly didn’t read it carefully enough the first time through. After my read-aloud, many students are able to explain and correct their errors without help.
Another Reboot report explains that critical thinking cannot be taught in isolation, nor can it be confined to only one discipline. Instead, it needs to be practiced regularly in all subjects because effective deductive thinking relies on background knowledge that is specific to each discipline. In other words, reasoning through an algebraic equation requires different content knowledge than analyzing a Shakespearean sonnet, the causes of the French Revolution, or trends in storm data.
Children can be taught deductive thinking by adults who engage them in conversation about complex problems to which there is no clear right or wrong answer. There are many issues on which reasonable, well-meaning people disagree. Encouraging young people to evaluate arguments based on how well they are supported by evidence helps strengthen their cognitive skills and prepares them for success at work and in life.
Elizabeth Breau, Ph.D. (she/her), is an award-winning writing coach and private English tutor. Her book, History According to SAT: A Content Guide to SAT Reading and Writing, won a silver medal in the teen category from the Nonfiction Authors Association. You can reach her at www.elizabethbreau.net.
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