Finding the Edges of Presumption
In the last post, we introduced Omni’s definition of presumption, which says that we should default to the minimum level of belief required by the available information. But that doesn’t mean starting the round with absolutely no positive beliefs.
Some judges claim to use a tabula rasa paradigm - meaning they try to be a “blank slate” that knows and thinks nothing, on which the debaters must write their ideas and theories. But even a tabula rasa judge has to accept these three starting points, which form the edges of presumption.
Common Knowledge is the information to which all debate participants are expected to have access.
There is some information that is so general and basic that we can safely assume that everyone knows it already. This is partly a pragmatic concession; if you had to prove absolutely everything without leaning on common knowledge, you’d run out of speech time hours before you got to your first point.
The most universally accepted form of common knowledge is language. A tabula rasa judge doesn’t expect you to teach them English; they brought that in with them. Other things that should already be understood:
We are in the United States of America.
Winter comes after autumn.
If you drop something, it goes down, not up.
If someone challenges a common knowledge claim, it’s reasonable to ask the judge to use common knowledge.
Opponent: How do we know dropped objects go down?
You: This is a waste of time. We’re all familiar with gravity in principle and practice. Please invoke common knowledge so I don’t have to waste the rest of the debate explaining it.
Common Sense is the body of claims that are obviously suggested by the available information.
In other words, if we apply basic logical principles to everything we know, we can safely imply some additional claims. Common sense includes basic moral values that you can expect everyone to hold, like “Human Life is good.”
Fact: Robert forgot his coat and went back to get it.
Fact: Robert lives 5 minutes away.
Fact: It is very cold outside and Robert will need his coat to be comfortable.
Common Sense Conclusion: We won’t see Robert for at least the next 10 minutes.
It’s only common sense if it’s obvious. Maybe Robert doesn’t need his coat. Maybe we’ll be inside most of the day. So maybe he’ll change his mind and come back sooner than 10 minutes without his coat. If we can’t obviously rule out that possibility, common sense doesn’t apply.
Again, common sense is a pragmatic concession. You have a few precious minutes to present your case; you can’t spare the tedious hours it would take to walk everyone through the obvious implications of your case.
That said, common sense is far from ironclad. As soon as it’s challenged, it stops working. That means you still need to be prepared to explain your analysis - even for seemingly obvious logic. You shouldn’t just tell the judge to invoke common sense.
You: The affirmative plan will kill people.
Aff: People dying isn’t bad.
You: Yes it is, and here’s why.
On the flip side, if you challenge common sense, the judge will probably be very skeptical. You should come loaded with great analysis and evidence.
Consensus is the body of claims on which both sides agree.
The judge is expected to choose from the positions in the round. They’re not supposed to throw out both cases and introduce their own case. So if they don’t hear their favorite argument, they can’t rule on it.
The other side of this coin: if both sides make the same claim, then that’s the only position available to the judge. The judge has to accept it no matter how silly it is. Since the negative almost always accepts something the affirmative said (like a definition), consensus is almost always in play to some degree.
This is one of the strangest things about judging debate. If one high schooler contests a study signed by 150 PhDs, the judge at least has the option to reject the qualified evidence. But if two high schoolers agree, the judge has no choice but to agree as well. That means the admission of your teenage opponent is more powerful than the most compelling evidence imaginable.
If you respond to an argument about saving life in a way that agrees that saving life is good, common sense and consensus combine to make the “life good” position ironclad. Even if you didn’t explicitly say it, you’ll have a tough time walking that position back later.
If it falls within one of the three overlapping circles of common sense, common knowledge, and consensus, the judge should have a positive belief about it.
You can think of presumption as “applying” to anything outside these circles. Once you wander beyond it, you need to provide support for your position. Since the resolution is outside, the affirmative starts the round with some work to do.
In the next post, we’ll show you a thought experiment that makes these concepts very simple.