You made the claim – now prove it
Somebody on the internet says vaccines cause autism.
Somebody else asks for evidence.
The response – “prove they don’t.”
No.
That’s not how this works. You made the claim. You prove it.
This is the burden of proof.
The principle is that whoever makes a claim is responsible for providing evidence to support it. When somebody shifts that responsibility by demanding you disprove their assertion, they’ve committed a logical error. The burden of proof is on the person making the positive claim. Not on everyone else to disprove every random thing somebody happens to assert.
If somebody claims there’s an invisible unicorn in their garage, they need to prove the unicorn exists.
Nobody else has to prove it doesn’t. The burden stays with the claimant. Always. The claim without evidence is just an assertion, and assertions don’t become true by getting louder or by not being disproven.
This gets weaponized constantly.
“The election was stolen.” Show me evidence. “You prove it wasn’t stolen.” That’s backwards. Accusations require evidence from the person making the accusation. The accused doesn’t have to prove their innocence. This is the structure of every functioning legal system in the world, and it exists specifically because the reverse structure makes it possible to destroy anyone you want by accusing them of something unprovable.
Conspiracy theories live in this territory.
“The government is hiding evidence of extraterrestrial contact.” Show me proof. “They destroyed all the evidence – that’s how you know it’s real.” This uses the absence of evidence as proof, which is the exact inversion of how evidence works. Absence of evidence is not evidence of presence. It’s just absence. The missing evidence doesn’t get to count twice, once as what should be there and once as proof of suppression.
Skeptics of new claims sometimes get told they need to disprove the claim before dismissing it.
That’s wrong. The default position when evidence is absent is not to believe the claim. Disbelief is the baseline. Belief requires support. Somebody saying “well, you can’t prove me wrong” has confused “I can’t be refuted” with “I’ve been confirmed.” Those are completely different, and the distinction matters.
The old Latin phrase for this is “onus probandi incumbit ei qui dicit.”
The burden of proof lies with the one who speaks. What you assert, you must support. Anyone who’s ever taken a philosophy class or a law class has encountered some version of this rule, because without it, rational discourse doesn’t really function. Anybody can claim anything, and everybody else has to prove infinite negatives to keep up.
This doesn’t mean skeptics get to be lazy.
If somebody is making the counter-claim that something is actively false – not just that they haven’t seen evidence for it – they’ve taken on a burden of their own. “I don’t see evidence for X” is different from “X is false.” The first is appropriate skepticism. The second is a positive claim that also needs support. Asymmetry between claim and doubt doesn’t mean doubters never have to show their work. It just means the initial burden was never theirs to carry alone.
When somebody tries to shift the burden, the response is simple.
“You made the claim. What’s your evidence?”
If they can’t answer, the claim is an assertion without support. Which means it doesn’t get accepted by default. It just gets shelved until somebody actually shows up with something. Skepticism is the starting position, not the counter-position somebody has to earn.
That’s the whole rule.