Failure to See False Conjunctions

The broader cognitive failure of not noticing when detailed, specific stories are being treated as more probable than their component parts warrant—an extension of the conjunction fallacy into everyday reasoning. Business plans that combine multiple specific assumptions (market size + adoption rate + pricing + execution timeline) are treated as plausible when each conjunction makes the overall plan LESS probable. Political narratives that weave together multiple specific claims are believed more readily than individual claims would be. The failure: each additional specific detail makes the story feel more plausible while making it statistically LESS probable.

When to use it

When multi-step plans feel convincing because they're detailed; when scenarios with many specific elements feel more likely than simpler ones; when evaluating any proposal that requires multiple independent conditions to be simultaneously true; when the conjunction fallacy is operating at the narrative rather than the example level.

How it can help

When evaluating any multi-part claim or plan: decompose it into its component conjunctions and evaluate the probability of EACH being true. Then multiply (or at minimum, recognize that the overall probability is lower than any single component). A business plan requiring favorable market timing AND successful product development AND competitor inaction AND customer adoption is the PRODUCT of all four probabilities—almost always much lower than any individual probability feels. The practice: 'for this to work, ALL of these things must be true simultaneously—what's the probability of THAT?'