(1) An individual's political philosophy depend on his ethics, which depends on his epistemology/metaphysics. If by ethics, epistemology, and metaphysics you mean explicit philosophy, this view is inapplicable to most people. Explicit philosophies tend to be mere rationalizations: self-conscious window dressing draped over the cognitive unconscious, which does most of the heavy cognitive lifting and does not think in terms of broad philosophical abstractions. Moreover, the genesis of explicit philosophies generally suggests that the causation tends to go in the other direction; that is to say, people tend to begin with a political philosophy, which they rationalize with various ethical rationalizations. Epistemology and metaphysics are usually ignored altogether; but when they are brought in at all, they are almost always brought in last. This is true even in Rand's case. Her early writings are dominated by politcal and ethical concerns; only later did she begin to dabble in metaphysics and epistemology
Now one way to skirt around these objections is to contend that individuals have "implicit" philosophies in which the political depends on the ethical, and the ethical on the epistemological, and so on. Everyone, Rand contended, has a philosophy; and if they don't have an explicit philosophy, they must have an implicit one.
The trouble here is that Rand's view of how implicit philosophies are developed and formed is heavily influenced by her false view of human mind. For Rand, an individual's implicit philosophy is formed by premises that have been integrated by the "conscious" mind:
Your subconscious is like a computer—more complex a computer than men can build—and its main function is the integration of your ideas. Who programs it? Your conscious mind. If you default, if you don’t reach any firm convictions, your subconscious is programmed by chance—and you deliver yourself into the power of ideas you do not know you have accepted. But one way or the other, your computer gives you print-outs, daily and hourly, in the form of emotions—which are lightning-like estimates of the things around you, calculated according to your values. If you programmed your computer by conscious thinking, you know the nature of your values and emotions. If you didn’t, you don’t....
The quality of a computer’s output is determined by the quality of its input. If your subconscious is programmed by chance, its output will have a corresponding character. You have probably heard the computer operators’ eloquent term “gigo”—which means: “Garbage in, garbage out.” The same formula applies to the relationship between a man’s thinking and his emotions.
As I have stated repeatedly, there is no evidence that the human mind works like this, and an enormous amount of evidence that it doesn't. Human behavior, whether political or otherwise, is not determined or strongly influenced by broad philosophical premises. Whether those premises are explicit or implicit is entirely irrelevant. Rand got this wrong in a very big way and it has enormous implications for her political philosophy. For Rand needs this doctrine to make her political philosophy realizable. In order for Objectivism to achieve its political ends, political philosophy must depend on ethics, which in turn must depend on metaphysics/epistemology; because if this is not so, then Objectivism becomes politically impotent.
Nathanial Branden once complained that Objectivism, like most ethical systems, lacks a "technology," a means by which Rand's values can be attained. Rand did, however, provide a technology for her politics: it is her theory of history. Unfortunately, this theory is wrong: it is based on a wildly inaccurate view of human nature. Human beings are not the playthings of philosophical premises. Rather, it's the other way around: philosophical premises are brought forward after the fact to serve as convenient excuses for decisions that are based on far more complex mental processes. Just as reason is not a source of motivation, so are philosophical premises insufficient to stir action. Human beings are motivated by desire, passion, sentiment, vested interest -- call it what you will; but they are not motivated or even influenced by such abstruse concerns the "hierarchy of knowledge" or "unit economy." Nor, as Rand seems to suggest, do such abstruse doctrines, which hardly anyone understands, have any influence on the actual political opinions people embrace. Try convincing anyone that the "hierarchy of knowledge" or "unit economy" logically leads to laissez-faire (i.e., that laissez-faire is logically entailed in those doctrines). Only an Objectivist would believe such a thing.
Real knowledge (as opposed to the artificial theories of pedantic theories such as promulgated in the Objectivist epistemology) is fundamentally practical and experiential: it's rooted in the sort of problem-solving forced upon us by the stresses of everyday life. Such knowledge always involves an important tacit, intuitive element. There is no evidence that exposure to the Objectivist epistemology causes people to think more accurately about reality. (If it were otherwise, how can we explain the Objectivist theories of human nature and history?) The human mind does not work that way. The cognitive unconscious plays a much larger role in thinking and decision-making than Rand could have ever imagined:
Recent cognitive science reveals a fascinating unconscious mind — a below-the-radar mind — that Freud never told us about. More than we realized a decade ago, thinking occurs not onstage but off-, out of sight. Studies of automatic processing, subliminal priming, implicit memory, heuristics, spontaneous trait inference, right-brain processing, instant emotions, nonverbal communication, and creativity unveil our intuitive capacities. Thinking, memory, and attitude all operate on two levels — conscious/deliberate and unconscious/automatic. “Dual processing,” today’s researchers call it. ...we know more than we know we know.
Since unconscious/automatic thinking processes play a large role in our conduct and our political beliefs, it is simply not true that our political and ethical notions depend entirely (or even mostly) on our epistemology and metaphysics. Our conscious philosophical ideas often have very little to do with the processing that goes on in the cognitive unconscious.
(2) The dominant philosophy of a given period determines its political conditions. Rand appears to have believed that each period of history has a dominant philosophy. Given the variety of philosophies that one finds in modern civilization, this is rather difficult to credit. But such were her views:
The power that determines the establishment, the changes, the evolution, and the destruction of social systems is philosophy. The role of chance, accident, or tradition, in this context, is the same as their role in the life of an individual: their power stands in inverse ratio to the power of a culture’s (or an individual’s) philosophical equipment, and grows as philosophy collapses. It is, therefore, by reference to philosophy that the character of a social system has to be defined and evaluated.
Just as a man’s actions are preceded and determined by some form of idea in his mind, so a society’s existential conditions are preceded and determined by the ascendancy of a certain philosophy among those whose job is to deal with ideas. The events of any given period of history are the result of the thinking of the preceding period.
These views illustrate Rand's theory of history. They are based on the view that human behavior arises from the premises which human beings have absorbed into their subconscious minds. Rand assumes that there always exists an "ascendant" or dominant philosophy which determines what sort of premises most people imbibe.
This view is grossly implausible, not merely because there is no such thing as a single dominant philosophy, but more importantly, because political ideologies are not determined solely by thinking or premises. As social psychologist Jonathan Haidt explains,
People don't adopt their ideologies at random, or by soaking up whatever ideas are around them. People whose genes gave them brains that get a special pleasure from novelty, variety, and diversity, while simultaneously being less sensitive to signs of danger, are predisposed (but not predestined) to become liberals. They tend to develop certain "characteristic adaptions" and "life narratives" that make them resonate -- unconsciously and intuitively -- with the grand narratives told by political movements on the left (such as the liberal progress narrative). People whose genes give them brains with the opposite settings are predisposed, for the same reasons, to resonate with the grand narratives of the right....
Once people join a political team, they get ensnared in its moral matrix. They see confirmation of their grand narrative everywhere [because of confirmation bias], and it's difficult -- perhaps impossible -- to convince them that they are wrong if you argue with them from outside their matrix. [The Righteous Mind, 316]
Since political ideologies are based partly on genetic predispositions which vary within the population (i.e., groups of people have different dispositions), political factions are a built-in feature of the human condition. Democratic societies will always divide into left-wing and right-wing factions; and amongst all this factionalism, Rand's laissez-faire can never emerge. Possibly, the reason why Rand insisted that a given age or period is determined by dominant philosophy (rather than by multiple philosophies) is that she understood the need for a broad consensus in order to establish laissez-faire. The two main political factions would have to believe in Rand's politics for it to become the law of the land. But if there is no dominant philosophy; if individuals are predisposed to varying types of political ideology; then the chances for laissez-faire are so close to zero that they might as well be zero. Rand's politics becomes utopian, not because it wouldn't "work" if it were tried (most politico-economic systems "work" after a fashion), but because it will never be tried.