Friday, June 06, 2008

Where does the burden of Proof Lie? [draft]

Lets say you enter into a debate with another person. Lets say both sides realise they have no strong reason for believing their own position except that they know it quite well. At the end of the debate we remain without any clear victory for either side - who's position gets the title of 'default position? who is left with the primary responsibility of 'disproving' the other side?

First we need to note that burden of proof is most importantly a norm for discourse and that agreement of both parties can change it. However we do have and need default rules for how burdens of proof are allocated.

Obviously the first is the side that does not have the preponderance of evidence also carries the burden of proof. As Al noted debate is in part like a tennis match where if it was that you made a point which on the face of it (to a neutral party) made your position look more likely - then your opponent is obliged to counter that argument before you need to present more arguments. But we want to be able to go a bit further than this obvious example.

For reference consider the legal approach
2. It is a general rule, that the party who alleges the affirmative of any proposition shall prove it. It is also a general rule that the onus probandi lies upon the party who seeks to support his case by a particular fact of which he is supposed to be cognizant; for example, when to a plea of infancy, the plaintiff replies a promise after the defendant had attained his age, it is sufficient for the plaintiff to prove the promise and it lies on the defendant to show that he was not of age at the time. But where the negative, involves a criminal omission by the party, and consequently where the law, by virtue of the general principle, presumes his innocence, the affirmative of the fact is also presumed.

the first point here is that the side proposing a conection or the existance of somthing bears the burden of proof. This is similar to Occams razor - "All other things being equal, the simplest position is the best." An example might be

Person A: "there are unicorns"
Person B: "there are no unicorns"

Person A bears the burden of proof.

2) the second point regarding to the plea of infancy is what I might term an "unnatural advantage". there are certain things you can be presumed to be able to prove (like your age) and if you don't it is to infer your not providing evidence is in itself evidence that that the truth detracts from your argument.


3) the current system does not carry the burden of proof. Lets say we have a current form of government - and a new group proposes a new form of government that is different but appears to be identical in it's benefits. In this case the people proposing the new system carry the burden of proof to allow for stable assumptions. For example our legal system might be no better than France's but to argue we should use France's in a court case would require considerable evidence.

Now a couple more that build on these

4) If the debate involves a hypothetical the side proposing the hypothetical bears the burden of proof. this is in part the fact that they are affirming a hypothetical is valid but the key issue is that it falls under the category of "unnatural advantage". The side which defines a hypothetical controls the nature of the debate and thus will be most able to argue their point - giving them the burden of proof encourages them not to use this advantage in a lazy manner.

For example if I say 'if fairy world exists then fairies are pink' it is up to me to provide an argument for that, prior to you needing to disprove it.

5) the side that initiated the debate (or wants to prove something) bears the burden of proof. Again this side takes the role of the affirmative but there is more to it than that.

The side that initiated the debate has pocked the time and nature of the debate, thy have also made it clear they are wiling to put effort into convincing the other side - it would be odd for them to now argue they don't need to make any points and that the other side needs to do all the arguing. Often the debate will be of the form "you are wrong or you are not wrong" as opposed to "you are wrong or I am right" if so then there is all the more reason for the initiator to ebar the burden of proof.

In a normal discussion this would take the form

in the wider debate person A and Person B contradictory theories

Person B : my theory is

Person A : Your theory is false

Person B : prove it

6) the side who’s position is least open to disproof carries the onus of proof. Lets say i have a theory that there exist invisible unicorns that you cant see or hear and you argue that there are unicorns that can be seen and heard. the suggestion is that I bear the burden of proof because by hypothesis my positi9on is harder to disprove so it is less productive to try to disprove it, further any lack of disprove of that theory is less evidence for it (consider Hempel's raven paradox).


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