The starting point of Objectivist Epistemology is the principle, presented by Rand as a direct consequence of the metaphysical axiom that "Existence is Identity," that Knowledge is Identification. Objectivist epistemology[9] studies how one can translate perception, i.e., awareness acquired through the senses, into valid concepts that actually identify the facts of reality.
Objectivism states that by the method of reason man can gain knowledge (identification of the facts of reality) and rejects philosophical skepticism. Objectivism also rejects faith and "feeling" as means of attaining knowledge. Although Rand acknowledged the importance of emotion in humans, she maintained that the existence of emotion was part of our reality, not a separate means of achieving awareness of reality.
Rand was neither a classical empiricist (like Hume or the logical positivists) nor a classical rationalist (like Plato, Descartes, or Frege). She disagreed with the empiricists mainly in that she considered perception to be simply sensation extended over time, limiting the scope of perception to automatic, pre-cognitive awareness. Thus, she categorized so-called "perceptual illusions" as errors in cognitive interpretation due to complexity of perceptual data. She held that objective identification of the values of attributes of existents is obtained by measurement, broadly defined as procedures whose perceptual component, the comparison of the attribute's value to a standard, is so simple that an error in the resulting identification is not possible given a focused mind. Therefore, according to Rand, knowledge obtained by measurement (the fact that an entity has the measured attribute, and the value of this attribute relative to the standard) is "contextually certain."
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