The main characteristic of this mentality is a special kind of passivity: not passivity as such and not across-the-board, but passivity beyond a certain limit -- i.e., passivity in regard to the process of conceptualization and, therefore, in regard to fundamental principles. It is a mentality which decided, at a certain point of development, that it knows enough and does not care to look further. What does it accept as “enough”? The immediately given, directly perceivable concretes of its background -- “the empiric element in experience.”
To grasp and deal with such concretes, a human being needs a certain degree of conceptual development, a process which the brain of an animal cannot perform. But after the initial feat of learning to speak, a child can counterfeit this process, by memorization and imitation. The anti-conceptual mentality stops on this level of development -- on the first levels of abstractions, which identify perceptual material consisting predominantly of physical objects -- and does not choose to take the next, crucial, fully volitional step: the higher levels of abstractions from abstractions, which cannot be learned by imitation. ...
The anti-conceptual mentality takes most things as irreducible primaries and regards them as “self-evident.” It treats concepts as if they were (memorized) percepts; it treats abstractions as if they were perceptual concretes. To such a mentality, everything is the given: the passage of time, the four seasons, the institution of marriage, the weather, the breeding of children, a flood, a fire, an earthquake, a revolution, a book are phenomena of the same order. ...
The two cardinal questions, the prime movers of a human mind -- “Why?” and “What for?” -- are alien to an anti-conceptual mentality. If asked, they elicit nothing beyond the conventionally accepted answers. The answers are usually some equivalent of “Such is life” or “One is supposed to.” ... The absence of concern with the “Why?” eliminates the concept of causality and cuts off the past. The absence of concern with the “What for?” eliminates long-range purpose and cuts off the future. Thus only the present is fully real to an anti-conceptual mentality. Something of the past remains with it, in the form of stagnant bits of a random chronicle, like a kind of small talk of memory, without goal or meaning. But the future is a blank; the future cannot be grasped perceptually. ...
In the brain of an anti-conceptual person, the process of integration is largely replaced by a process of association. What his subconscious stores and automatizes is not ideas, but an indiscriminate accumulation of sundry concretes, random facts, and unidentified feelings, piled into unlabeled mental file folders. This works, up to a certain point -- i.e., so long as such a person deals with other persons whose folders are stuffed similarly, and thus no search through the entire filing system is ever required. ...
A person of this mentality may uphold some abstract principles or profess some intellectual convictions (without remembering where or how he picked them up). But if one asks him what he means by a given idea, he will not be able to answer. If one asks him the reasons of his convictions, one will discover that his convictions are a thin, fragile film floating over a vacuum, like an oil slick in empty space -- and one will be shocked by the number of questions it had never occurred to him to ask.
This kind of psycho-epistemology works so long as no part of it is challenged. But all hell breaks loose when it is -- because what is threatened then is not a particular idea, but that mind’s whole structure. The hell ranges from fear to resentment to stubborn evasion to hostility to panic to malice to hatred. ...
It is the fundamentals of philosophy (particularly, of ethics) that an anti-conceptual person dreads above all else. To understand and to apply them requires a long conceptual chain, which he has made his mind incapable of holding beyond the first, rudimentary links. If his professed beliefs -- i.e., the rules and slogans of his group -- are challenged, he feels his consciousness dissolving in fog.
(From Ayn Rand, Philosophy: Who Needs It)