Burden of Proof

'Prove you are not an alien.' How do you answer that demand? Any silence will be read as a confession. The burden of proof is the rule that protects us from this trap and makes discussion possible.

• **Courts:** presumption of innocence is the foundation of the rule of law. The prosecution proves; the defense has the right to remain silent
• **Medicine:** the FDA requires proof of efficacy and safety BEFORE a drug reaches the market, not after complaints
• **Startups:** an investor does not need to prove the idea will not work. The founder must prove it will

Burden of proof

**The burden of proof** is the obligation of the side advancing a claim to provide sufficient grounds for it. 'Whoever asserts must prove' (onus probandi). Without this principle anyone could assert anything and demand that others refute it.

**Basic rule:** the one who asserts bears the burden of proof. 'God exists' is for you to prove. 'God does not exist' is also for you to prove. 'I do not know' is a neutral position with no burden.

**The error of shifting the burden:** demanding that the opponent prove an absence (prove a negative). 'Prove you are NOT a criminal' is impossible: you cannot prove the absence of every crime. The burden lies with the accuser.

Null hypothesis

**The null hypothesis (H₀)** is the default position adopted until evidence to the contrary appears. In science it is usually 'no effect' or 'no difference'. The burden of proof rests on the alternative hypothesis (H₁).

**Asymmetry of evidence:** the null hypothesis cannot be 'proved'. It can only fail to be rejected. Absence of evidence against H₀ does not mean H₀ is true. Perhaps we just failed to detect the effect (insufficient power).

**Why this way?** The alternative is chaos. If every claim about an effect were considered true until refuted, we would believe every untested drug, every conspiracy theory, every pseudoscience. The null hypothesis is a filter against noise.

Presumptions

**A presumption** is an assumption taken as true until evidence to the contrary appears. The presumption of innocence: the defendant is considered innocent until guilt is proved. This is not a belief in innocence. It is a rule about who must prove.

**Different contexts, different presumptions:** - **Criminal law:** presumption of innocence; the burden lies with the prosecution - **Civil law:** burden on the plaintiff, but a lower standard ('more likely than not') - **Science:** presumption of no effect (H₀) - **Medicine:** 'Do no harm'. A new treatment must prove safety

**Presumptions as heuristics:** presumptions reflect experience. Most defendants in democratic countries are innocent. Most claimed effects do not replicate. Most products are safe. A presumption saves resources by placing the burden on whoever asserts something against the base rate.

Shifting the burden

**Shifting the burden of proof** is a rhetorical move where the side that should prove instead demands that the opponent prove the opposite. 'Prove that God does not exist' instead of providing evidence for existence.

**Signs of burden shifting:** - 'You cannot prove that it is not true' offered as an argument for the truth - Demanding refutation of an unfalsifiable claim - 'Until proved otherwise, I am right by default'

**Legitimate burden shift:** the burden can lawfully move once the initial claim is justified. If the prosecution has presented evidence, the defense must address it. A prima facie case is enough evidence to shift the burden.

Key Ideas

• **Burden of proof** lies with the asserter; the opponent's silence does not confirm your claim
• **Null hypothesis** is the default position ('no effect'). It cannot be proved, only fail to be rejected
• **Presumptions** reflect base rates and the cost of errors; different contexts require different standards
• **Burden shifting** is a rhetorical error; a legitimate shift requires a prima facie case

Related Topics

Burden of proof connects to:

• Scientific method — Falsification and the null hypothesis as standards
• Falsifiability — Unfalsifiable claims can neither be proved nor refuted
• Logical fallacies — Argument from ignorance is a special case of burden shifting

Вопросы для размышления

• Recall a dispute where you demanded that the opponent 'prove I am wrong'. Was that legitimate or a burden shift?
• Which beliefs do you hold without positive evidence, simply because 'no one has proved otherwise'?
• How does your standard of proof change with the stakes of the decision?

Связанные уроки

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