Introduction to Objectivist Epistemology

Introduction to Objectivist Epistemology is Ayn Rand's monograph on the theory of concepts — how a mind forms abstractions from perceived particulars, and why the abstractions so formed are objective. Usually abbreviated ITOE, it is the most technical of her books and the primary source for the whole of Objectivist epistemology.

“The issue of concepts (known as "the problem of universals") is philosophy's central issue.”
~ Ayn Rand, Introduction to Objectivist Epistemology

The problem it sets out to solve

Everything a person perceives is a particular: this table, that man, this shade of blue. But nearly everything he knows is held in the form of abstractions that refer to no particular in especial — "table", "man", "blue". Philosophy has asked for two and a half thousand years what those abstractions refer to.

Rand's account of the historical answers, and why she rejected each:

Platonic realism — universals exist in a separate dimension, and particulars are imperfect copies. This detaches concepts from the reality they were formed to describe; see Intrinsicism.
Aristotelian realism — universals exist in the particulars, as a shared metaphysical essence. Closer, but it still treats the abstraction as something found rather than performed.
Nominalism — universals are only words, arbitrary labels attached to arbitrary groupings. This makes all classification conventional and knowledge subjective; see Subjectivism.

Rand's answer is that concepts are neither found in reality ready-made nor invented at will. They are formed by a specific mental process, performed on real similarities, and are objective because the process is. See Objectivity.

The central mechanism: measurement omission

The book's distinctive contribution is the account of what the mind does when it abstracts. Similar concretes differ from each other in measurement along some shared attribute — two tables differ in length, width and height, but both have length, width and height.

A concept is formed by isolating concretes that share an attribute, then omitting the particular measurements while retaining the attribute. The formula Rand gave is that the measurements must exist in some quantity but may exist in any quantity. See Measurement omission and Conceptual Common Denominator.

Two consequences run through the rest of the book:

Concepts are open-ended. "Man" subsumes every man who has lived, lives or will live, including those about whom nothing is yet known, because the concept omits the measurements that distinguish them.
Unit-economy. A mind can hold only a few items in awareness at once. Condensing an unlimited number of concretes into a single unit is what makes conceptual knowledge possible at all. See Crow-epistemology.

The two editions

The material first appeared as a series in The Objectivist in 1966–67 and was issued as a book in 1967. The second edition (1990), edited by Harry Binswanger and Leonard Peikoff after Rand's death, is the one now in print and the one this wiki cites.

Its addition is the appendix: an edited transcript of epistemology workshops Rand held between 1969 and 1971, in which professional philosophers, physicists and mathematicians questioned her on the theory. The workshop material is in question-and-answer form and is often clearer than the monograph, particularly on axiomatic concepts, implicit concepts and the philosophy of science.

Common misunderstandings

That it is an introduction to Objectivism. The title means an introduction to the epistemology. It presumes a reader who already knows the philosophy in outline.
That measurement omission requires literally measuring anything. The measurements are omitted, not taken. What the process requires is that the attribute be one that could be measured, not that anyone has done so.
That definitions are arbitrary conventions. Rand's chapter on definitions argues the opposite: a definition names the fundamental characteristic of the units, and is objective and contextual rather than either arbitrary or eternal. See Rule of Fundamentality.
That the theory only concerns concepts of physical objects. Chapter 4 extends it to concepts of consciousness, and the same mechanism handles concepts of relationships, of methods and of measurement itself.

Discussion

References

Rand, Ayn. Introduction to Objectivist Epistemology. 2nd edition, edited by Harry Binswanger and Leonard Peikoff. Meridian, 1990.
Peikoff, Leonard. "The Analytic-Synthetic Dichotomy", in the same volume.
Peikoff, Leonard. Objectivism: The Philosophy of Ayn Rand, chapters 3 and 4.

External links

Concepts at the Ayn Rand Lexicon