Against Tabula Rasa, Part 1: Is Everything Up for Grabs?

This is the first in a series of five posts on tabula rasa judging–i.e., the view that judges should not use their pre-round opinions to evaluate in-round disagreements. Using pre-round opinions in this way constitutes “intervention,” and the guiding principle of tabula rasa judging is to intervene as little as possible. That is not a very clear statement of the view, and I try to make it more precise in a later post in this series. But, in this first post, I argue for one claim:
Not everything is up for grabs in a debate. The judge can assume rules of valid inference when evaluating debates, and these rules might not be contestable.

In the next post, I make another claim: evaluating arguments in a debate often requires what many consider to be “intervention”–that is, using the judge’s own pre-round opinion to decide the outcome of an in-round dispute.

But there is an easy way around these problems. The solution, which I outline in the third post, requires the judge’s starting points to be as neutral as possible. In the fourth post, I explain why the solution fails. And in the final post, I explain why my own view of the judge’s starting points is better.

 

My first argument is about rules of inference. A rule of inference is how you draw conclusions from premises. For example, one of our rules of inference is modus ponens:

If p, then q.

P.

Therefore, q.

For example:

If it is wrong to deny due process guarantees to any person under any circumstances, then it is wrong to deny due process guarantees to non-citizens accused of torture.

It is wrong to deny due process guarantees to any person under any circumstances.

Therefore, it is wrong to deny due process guarantees to non-citizens accused of torture.

Another rule of inference is modus tollens:

If p, then q.

Not-q.

Therefore, not-p.

For example:

If every person has an inviolable right against coercion, then taxation is wrong.

Taxation is not wrong.

Therefore, it’s not the case that every person has an inviolable right against coercion.

There are other rules of inference. But here’s the point: the judge must take these rules of inference for granted.

If all rules of inference were up for debate, how would you decide which rules of inference to accept? You can’t just evaluate the arguments on each side. When you take an argument to justify a conclusion, you’re using a rule of inference. So (and we’re using a rule of inference here), the rules of inference aren’t up for debate. The judge walks into the round with them.

This isn’t to imply that logic is never controversial. The controversial ones might be up for debate. I didn’t say that all rules of inference must be assumed and non-contestable. But some of them must be.

What does this imply for tabula rasa judging? It means that the judge’s obligation isn’t to intervene as little as possible. The constraint is not possibility, but rationality–i.e., obeying the rules of valid reasoning. This will set up my view of judging in terms of credences, which I’ll get to later.

  • pdve

    I agree that rules of inference must be assumed, but i'm not sure why they should also be non-contestable.Suppose a debater contests the validity of modus ponens or modus tollens (e.g. McGee 1985; Yalcin 2012). Suppose further that the debater's strategy totally relies on abandoning classical logic or classical semantics. If I were to judge this round in such a way that I assumed the validity of modus ponens or modus tollens and ignored any in-round arguments to the contrary, then the winner would not be the "better debater" but the debater whose views on logic correspond to my own. This strikes me as an unfairness that should be avoided. Scenarios such as these recommend the following principle: judges should not use a pre-round opinion to evaluate an in-round disagreement when the pre-round opinions is the topic of the in-round disagreement. This principle is consistent with a tabula rasa conception of judging, but it is also consistent with other conceptions of judging where pre-round opinions can used. This principle merely restricts how a judge's pre-round opinions can be used, i.e., judges can use their pre-round opinions to evaluate in-round disagreements so long as those pre-round opinions are not the topic of the in-round disagreements.

    • After thinking about it, I'm inclined to agree with you. But I'm still not sure how I would evaluate a disagreement about modus ponens without using modus ponens (even if just as a rule of thumb). If there is a way, I'd accept your view. But if not, I think I can go a step down from non-contestable to something like, assuming it until a debater persuades me to change my mind.