Peter van Inwagen on Burden of Proof in Philosophy

Andrew Bailey sends the following quotations for our delectation:

"(When a philosopher says, "The burden of the proof lies on you", he means, "You must deduce your conclusion from the truths of immediate sensory experience by means of an argument that is formally valid according to the rules of elementary logic; I on the other hand may employ any dialectical tactic I find expedient".)"

 

-PvI, An Essay on Free Will, p.18

 

"Where does the burden of proof lie in a philosophical debate? In a debate of the type we are imagining, the answer is clear--in fact, trivial. The burden of proof lies on the person who's trying to prove something to someone."

 

-PvI, The Problem of Evil, p.46

 

Notice that the thesis encoded in the second is a little different (and much more plausible) than "he who asserts must prove".

I'd have to examine the context, but the second quotation seems to support what I was saying yesterday, namely, that burden-of-proof considerations have no non-trivial role to play in philosophical discussions. 

 

It is quite otherwise in the law, which is where we get the notion of burden of proof (BOP) and the correlative notion of defeasible presumption (DP).  As N. Rescher remarks (Presumption and the Practices of Tentative Cognition, p. 13),  both are at root legal conceptions dating back to Roman law.  Now court-room proceedings are essentially both practical and adversarial:  what is in dispute is not a matter of theory, but a matter bearing upon such things as a person's wealth and liberty.  Thus it makes perfect sense that the BOP should be placed on the plaintiff in a civil case and the state in a criminal case, which is equivalent to granting to the accused a defeasible presumption of innocence.  The onus probandi rests on those who make allegations.  Thus it makes sense within the law to maintain that

 

Necessitas probandi incumbit ei qui dicit non ei qui negat.

The need for proof lies with him who affirms, not him who denies.

 

Now to my way of thinking, philosophy-as-inquiry is never adversarial, and is primarily theoretical.  This is part of my reason for thinking that the fundamentally legal notions of BOP and DP ought not be imported into philosophy-as-inquiry.  It strikes me as very clear that one who makes an accusation bears the burden of proof.  But it is not so clear that one who makes an assertion bears a burden of proof. 

 

Indeed, it is either false or meaningless. For if van Inwagen asserts that there are no modes of being, and I assert that there are, then we both make assertions.  So if he who asserts bears a burden of proof, then we both bear the burden of proof -- which trivializes the very notion of BOP.

 

So I am skeptical about the importation of the fundamentally legal concept of BOP from that essentially adversarial and practical dialectical context into philosophy-as-inquiry.  But this is a complicated topic.  I'll say some more tomorrow.

 

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Are Burden-of-Proof Considerations Relevant in Philosophy?

Comments

[Lukas Novak]

Dear Bill,

I don't agree with you. I don't think that an adequate analysis of a philosophical dispute, or of a (facet of a) theoretical problem, is "Party A claims X and party B claims non-X" (or: "is X or non-X the case?"). Rather, the elementary analysis should go: "Party A claims X and party Y disputes that claim" (or: "Is believing X justified or not?"). A separate problem then may be: "Party B claims non-X and party A disputes that claim" (or: "Is believing non-X justified or not?").

In one way, the matter of the burden of proof is indeed trivial: whoever makes a claim, bears the burden of proof. But it is often not trivial who is making a claim! People often confuse disputing a claim with making the opposite claim. To try to sort this out is, in effect, to argue a "burden of proof" issue.

Furthermore, it seems to me that there are some cases of legitimate "defeatable presumptions" in philosophy; i.e. cases where it is legitimate even to claim something without proof. These are the common-sense beliefs like that there are more than one individuals in the world, that genuine change exists, that some entities endure in time, etc.

[BV]

Thanks for commenting, Lukas.

>>People often confuse disputing a claim with making the opposite claim.<<

It would be nice to have some examples of this confusion. Consider a bit of dialog:

A. The law of noncontradiction (LNC)is a law of thought merely.

B. I dispute your claim. LNC is not a law of thought merely; it is also a law of extramental reality.

In this example, B disputes what A says by making a counter-claim, a counter-assertion. Both are asserting. It strikes me as foolish to ask who has the BOP. Wow decide such a question?

Suppose you say the BOP rests on the one who questions the received or traditional view. Then the BOP would be on A. But if you say that the BOP rests on the one who makes the stronger claim, the more committal claim, then the BOP would be on B.

Now the second point you make is much better. It makes good sense to say, for example, that there is a defeasible presumption in favor of the reliability of memory as a source of knowledge, and thus that the BOP would be borne by someone who is out to discredit memory as a source of knowledge.

But note that 'BOP' and 'DP' are now being used in senses that are only analogous to the senses they have in the law. The presumption of epistemic innocence must not be confused with the presumption of innocence in a court of law.

[Lukas Novak]

Bill,

concerning your dialogue: IMO both A and B bear a burden of proof here. For that reason, it is an unlucky start of a dispute - because it is in fact start of two disputes at once, and a dialectical confusion is likely to arise. In order that the dialogue be fruitful, B should not have put forward a negation of A's claim as his own claim, but simply refuse to accept A's claim until proved (this is the meaning of the rule Necessitas probandi incumbit ei qui dicit non ei qui negat - "negare" here has the technical meaning of "to refuse to concede until proved", according to the rules of disputation). If A failed to produce a proof, his case would fail. If he produced one, his case would succeed unless and until B attacked that proof, thus prompting for another argument to "restore" the former one. And so on, until one of the parties failed to do their duty. Only if A was the one who so failed, it would be in place for B to state his opposite meaning as a claim, if he wishes, with the burden of proof incumbent.

There are three, not two possible dialectical states of a proposition: (i) proved (ii) disproved (iii) neither. The "burden of proof" just means that the default state is (iii).

Perhaps our difference boils down to this: you think that a dispute is about truth or falsity of a proposition, whereas I think that it is about validity or invalidity of rational support of a proposition. Whereas from the former point of view the dialectical situation comes out as symmetric, in the latter view it is inherently asymmetric.