How much proof must a historian offer?

PROBLEM: In communicating his ideas to others, how much proof must a historian offer?

IMAGINARY EXAMPLE: Let's say historian Dr. A writes an essay whose purpose is to persuade readers to adopt a certain idea. His publisher, the Journal of the Intellectual History of France in the Central Middle Ages, sets a length limit at only 2000 words. Within that limit, the historian must present and prove his thesis: Siger of Brabant--a teacher of liberal arts in the university at Paris, c. 1265--was the first academic to try to establish philosophy as an autonomous discipline, that is, a field of university study that is independent of the demands of the "science" of theology (the mistress whose handmaiden is philosophy).

Given the circumstances (for example, the brevity of the essay and the fact that an essay allows no question-and-answer process for clarification or elaboration), Dr. A realizes that he must hold modest expectations of success. He intends only to sketch the basic points of a line of proof for his theme.

In Dr. A's essay, a single sentence states his theme. Directly or indirectly, the other sentences (all statements about past reality) are elements of his proof of his theme. By citing primary and secondary sources in medieval and modern texts, the essay's footnotes elaborate some of the proofs or at least lead readers to further information and argumentation. By citing examples at various stages of his argument, he is connecting his theme to (past) reality, even if he is not offering a full, explicit chain of proof back to sense-perceptible reality.

Dr. A's essay is completely objective (that is, the conclusions follow logically from facts of reality) and yet it contains not even one self-evident statement. A proof is one form of validation, the form in which a thinker connects evidence (ultimately, sense-perceptible) step by logical step to his conclusion, the one to be proven.

In the chain of Dr. A's proof, reaching back from the theme to sense-perceptible reality, there is a "gap" between the lowest links in the chain of his proof and the sense-perceptible reality subsumed by his theme. This gap often appears in historical writing, wherein the "reality" of the past consists in a few artifacts--such as a thousand-year-old manuscript or an inscription chiseled on a stone monument--surviving from past times; such evidence must be interpreted and is not self-evident.

What an objective writer ultimately relies on to connect his theme to sense-perceptible reality, besides the immediate and necessarily abbreviated argument (proof) he presents, is the fact of shared context. In our example essay, Dr. A defines his intended audience as being at least graduate students in the field of medieval French history, specializing in 13th Century philosophical transmission.

By defining his audience in this narrow way, he is trying to ensure that he and his target readers have the same context--that is, the same set of relevant knowledge outside the immediate content of his essay. Presumably the writer and his readers can then, on demand, connect that shared context to sense-perceptible reality. For instance, given his theme and his definition of audience, Dr. A does not need to prove that a university existed in Paris in 1265. What he does need to prove, to some contextually-determined degree, is that Siger held and advocated the idea of autonomy for philosophy as a field of study in the university.

Especially outside the field of philosophy, objective writers seldom need to prove their themes down to the level of explicit self-evidencies. The writers and their intended audiences share a context of knowledge which, in turn, presumably they can, on demand, connect to sense-perceptible reality.

CONCLUSION. A writer needs to offer enough proof of his theme to achieve his purpose for the audience he is addressing in the chosen circumstances. All three factors--the writer's purpose, his intended audience, and his circumstances--set the context that drives the writer's decision to provide such-and-such amount of proof for his theme.

Burgess Laughlin
Author, The Power and the Glory: The Key Ideas and Crusading Lives of Eight Debaters of Reason vs. Faith

P. S. 1 -- Corollary: Criticizing an author, in a particular piece of writing, for "failing" to prove his case down to sense-perceptible reality is to expect the impossible. An author need only provide as much proof as his purpose, audience, and circumstances demand. In certain contexts, he can rightly assume that his audience can take the remaining steps on a path to a complete proof.

P. S. 2 -- My January 2, 2008 article on self-evidency was preliminary to this article on amount of proof. This article on amount of proof, in turn, is preliminary to another problem I have been wrestling with: What is the proper relationship between an intellectual and his audience? What do they owe each other, if anything? Originally these various subjects were a single cognitive traffic-jam. At least I have now sorted them onto three--interconnecting--roads. I am making progress.

Meaning of "self-evident"?

In Objectivism, the phrase "self-evident" refers to a certain kind of truth, that is, a certain kind of statement that identifies a fact of reality. Example statements about reality are:
- This table is brown.
- My computer is a Mac-mini.
- Most dogs bark.
- To survive and flourish, man requires freedom in society.
- Existence exists.

Which of these statements are self-evident? Ayn Rand observes: "The layman's error, in regard to philosophy, is the tendency to accept consequences while ignoring their causes--to take the end result of a long sequence of thought as the given and to regard it as 'self-evident' or as an irreducible primary, while neglecting its preconditions. [...] As a philosophical detective, you must remember that nothing is self-evident except the material of sensory perception."[1]

In the philosopy of Objectivism, there are no self-evidencies except philosophical axioms. An example axiom is: "Existence exists."[2] You look around, and you see things that are. Proof, in the form of an argument, is required to validate all other ideas.

An axiom is the widest of all abstractions, but it requires no further validation than sense-perception. The same rule applies, I would suggest, to particular, sense-perceptible concretes. An example is: "This table is brown." The fact that this particular table exists and is brown is self-evident to me. Not self-evident are what it is, in all its characteristics (weight, dimensions, and so forth); how it works (screws hold it together); and how much value it has for me (resale, very little).[3]

CONCLUSION. "Self-evidency" refers to the fact that sense-perception--and only sense-perception--is cognitively self-justifying, requiring no proof. "Self-evident" applies only to (1) philosophical axioms, which are validated by reference to sense-perception, and (2) the existence (but not the nature) of individual sense-perceptible entities. So, ironically, "self-evident" applies only to particular, sense-perceptible concretes and to the widest of abstractions.

Burgess Laughlin
Author, The Power and the Glory: The Key Ideas and Crusading Lives of Eight Debaters of Reason vs. Faith

[1] Ayn Rand, "Philosophical Detection," Philosophy: Who Needs It?, p. 15. I assume "sensory perception" here includes introspection of mental concretes. (For mental concretes: Ayn Rand, Introduction to Objectivist Epistemology, 2nd ed., p. 156.)
[2] Leonard Peikoff, Objectivism: The Philosophy of Ayn Rand, p. 8.
[3] In informal discussion, an objective speaker might loosely say something like this: "The conclusion is self-evident." What he would mean is: "You who are listening to me have all the information you need. Draw a conclusion. And there is only one conclusion you can draw logically within the limits of our shared knowledge."