A classically constructed rational argument consists of just three parts:
Evidence (facts; “given these data points”)
Arguments (logic; “and this chain of reasoning”)
Conclusions (results; “it follows that…”)
Within the rules of Classical Rationality, then,
IF you accept my Evidence,
AND IF you accept my Arguments,
THEN you must ALSO accept my Conclusions.
Good so far? Good.
A classically constructed rational argument is also vulnerable to three lines of attack. But they aren’t the same three lines.
Two are of course familiar:
You can attack my Evidence (“your facts are wrong”);
You can attack my Arguments (“your logic/reasoning is fallacious”)
But the third is strangely slippery:
You can attack my Standard of Evidence (“your facts are right, but you’ve cherry-picked them to support your position”).
Still good? Let’s unpack.
A Standard of Evidence (also known as a Methodology) is a bit like scaffolding.
Built around an argument-to-be, it
Limits the argument’s scope
Supports its construction
Enables its future inspection
By design (and by definition!), an argument’s Standard of Evidence is necessarily both selective and predetermined. Once selected, it stays set. It cannot be altered without robbing Classical Rationality of its persuasive power.
Changing it mid-project starts an avalanche that
alters the Evidence,
unsettles the Arguments,
and invalidates the Conclusions.
So choosing a standard of evidence is not a trivial problem.
Scientific papers implicitly recognize the Standard of Evidence problem’s importance by listing it before the other sections:
FIRST, describe the Methodology (or Experimental Design)
NEXT, summarize the Evidence (or Data Collected)
ONLY THEN, make the Arguments (or Discussion)
FINALLY, draw the Conclusions (or Recommendations)
But there is a dodge going on here! The dodge is at once simple, effective, and fatally short-sighted:
Scientific arguments are persuasive to other scientists, because an implicit methodological consensus already exists within the scientific community.
By and large, the scientific community has already agreed WHICH methodological approaches should be allowed. If you can meet the established scientific standard, then you have a fair chance at persuading scientific minds.
BUT:
Standard-of-Evidence attacks are strangely slippery because they are launched from OUTSIDE the community consensus.
Substitute “Republicans,” “Democrats,” or “News Media” for scientists in the paragraph above, and the problem becomes clear. Ingroup persuasion isn’t convincing to outsiders who don’t share the community standards.
SO:
Consensus is what enables rational persuasion. NOT the other way around. This limit is baked into Classical Rationality.
Classical Rationality cannot create consensus. That is not within its persuasive power.
How does Classical Rationality persuade? By mapping the unsuspected extent of an ALREADY EXISTING consensus, as indicated by the presence of a mutually accepted Standard of Evidence.
And the rules of Classical Rationality don’t tell you how to find one, do they?
But that’s a job for another post.