Rules Of Thumb: How To Make Dumb Decisions

Rule-of-thumb thinking—or heuristic-based thinking, the use of mental shortcuts—simplifies decision-making but can result in biased, suboptimal, or oversimplified conclusions and choices. While heuristics can be priceless for rapid decision-making, using them too often results in high error rates. Particularly in complex, high-stakes situations. You don’t want them to bite you. Avoiding this trap boils down to critical awareness, deliberate thinking, and the use of systematic and structured frameworks, models, and tools.

Recognize when heuristics are at play. This is always the first step—to identify when you are using a rule of thumb. Common heuristics are the availability heuristic—basing judgments on information you can easily remember—and the representativeness heuristic—judging people based on stereotypes. For example, if you assume a product or service is superior just because it is more expensive than the alternative, you are probably falling for something. Question how you arrived at your conclusion. Identify whether it is based on incomplete or oversimplified reasoning. Low-quality logic.

Slow down. Engage in reflective thinking. Heuristics thrive in fast, reactive decision-making. Suffocate them by slowing down and embracing proactive choices. Counteract the tendency directly, deliberately shifting back a gear or two when met with important decisions. Use frameworks like impact-effort matrixes and five-whys, tools like inversion or second-order thinking, and various mental models to break problems down into core components instead of relying on surface-level data. For example, if you catch yourself following a trend because “everyone else is doing it”, pause and assess the evidence and pros and cons of doing so. Does it align with your objectives, or are you just trying to be “popular”?

Seek evidence. Verify assumptions. Rules of thumb are based on generalized information. They may not hold true under specific contexts. As a rule, the assumptions collapse right as you leave their initial scope and gather empirical data. For example, using the 80/20 rule, ensure you have correctly identified the 20 percent through evidence rather than assuming the principle to apply universally. What facts support this? Why did you come to that conclusion? How? The more questions you ask now, the less you have to explain yourself for making a dumb choice later.

Use counterexamples. Seek alternative perspectives. Try to prove yourself wrong. This is an effective way to break free from heuristics that serve to confirm your beliefs. For instance, if you believe a particular investment is safe just because “it has always performed well”, find cases where similar investments failed to see it in a different light. Your brain may want to agree with your assumptions, but they are not always correct. Challenge it. Try a tool like inversion while you’re at it, helping you uncover risks or flaws you skimmed over when using rule-of-thumb logic.

Apply a systematic decision framework. Think a bit more than your brain wants you to. Decision frameworks like impact-effort matrixes, SWOT analyses, and decision trees act as structured ways to evaluate decisions. They ad litteram place you in frames that work to make your decisions better. For example, when hiring a candidate, instead of relying on anchoring—overly valuing the first piece of data—use a strengths-weaknesses analysis to evaluate how their skills, experience, and ethical notions fit into the organization.

Reflect on past decisions and their outcomes. Regularly review them. See where you used rules of thumb. Assess how effective they were—probably not very. Identify patterns where they did work well. Keep using them there. Elsewhere, apply frameworks, thinking tools, and mental models or their combinations to boost your thinking and not repeat the mistakes. Balance the efficiency of heuristics with the effectiveness of evidence-based thinking. Get the best of both worlds.