F105 • Informal - Evidence
Also known as: Onus Probandi, Shifting the Burden, Burden of Proof, Shifting the Burden of Proof, Proving a Negative
We make a claim and then, when asked for evidence, turn the question around: "Well, prove that I am wrong." It feels like a fair move -- after all, if someone is going to challenge you, should they not bring their own reasons? But the person who introduces the claim is the one who owes it support, and asking others to disprove it is a way of quietly slipping out of that obligation.
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In everyday life, most of our claims do not get challenged, and for good reason -- "I had coffee this morning" does not need a lab report. That easy flow of trust is a feature of how we communicate. It keeps conversations moving. The trouble starts when we extend that same casual trust to claims that actually need support. When someone says something surprising, extraordinary, or consequential, the normal expectation is that they will have reasons. Reversing the burden -- asking the skeptic to provide evidence against the claim instead -- borrows the social ease of casual conversation and applies it where it does not belong. It feels conversationally smooth, but it quietly removes the obligation to support the very claim being made. We have all felt the pull of this: someone challenges something we believe, and our first instinct is not to defend the belief but to push the challenge back. That instinct is natural, but following it means the claim never actually gets examined.
| In most of our daily interactions, we do not demand evidence for every claim, and we should not. 'It is cold outside' does not need a thermometer reading. The burden of proof becomes important when claims are surprising, consequential, or contested -- and knowing which claims cross that threshold is itself a skill worth developing. |
| When someone has already provided evidence and the skeptic simply ignores it and keeps asking for more, the obligation does shift. Meeting the burden of proof is a real thing, and once it has been met, it is fair to ask the other side to engage with the evidence that has been presented. |
| You might notice yourself feeling defensive when asked for evidence -- that defensiveness is often the first sign that you are about to flip the burden rather than meet it. |
| Watch for the conversational reflex of answering a question with a question. 'Why do you believe that?' answered with 'Why do you not?' is the pattern in its most compressed form. |
| Pay attention when a claim is introduced and then, instead of being supported, the conversation shifts to whether anyone can disprove it. The claim has been quietly promoted from assertion to default without doing the work. |
| Notice the difference between 'I believe this because...' and 'You have not shown me why I should not believe this.' The first is meeting the burden; the second is redirecting it. |
| Thinking that the burden of proof never moves. In an ongoing conversation, once someone has provided substantial evidence, it is reasonable to ask the other side to respond. The burden shifts -- but only after it has been met first. |
| Not recognizing that some contexts have explicit rules about burden of proof. Legal systems, scientific peer review, and formal debates all have established conventions about who proves what, and those conventions are not arbitrary. |
| Treating every request for evidence as an unfair burden. Asking 'what makes you think so?' is not an attack -- it is the basic currency of thoughtful conversation. |
| Burden of Proof Fallacy |
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| Placing the burden of proof on the person questioning a claim rather than on the person making the claim. |
| The person making a positive claim has the responsibility to provide evidence. Demanding others disprove your claim reverses proper burden of proof. |
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