Epistemology: Knowledge Theories from Plato to Empiricism

Epistemology: Foundations of Knowledge

Plato: Knowledge vs. Opinion

Plato distinguishes between science (knowledge) and opinion. Opinion is superficial knowledge based on the senses. The objects of opinion are appearances, material objects, and changing physical reality. In the world of opinion, there is no true knowledge, but it is distinct from ignorance. Science is knowledge of the eternal and immutable essence of reality—the Ideas—which can only be reached through reason.

Aristotle: Integrating Senses and Reason

Aristotle also distinguishes between sensible and rational knowledge, but in a manner different from Plato. He considers sensory input a source of knowledge. Rational knowledge is achieved through capturing the universal essences of concrete things. The senses capture specific realities, and then reason develops concepts that express the universal essences of these concrete things.

Rationalism (Descartes): The Primacy of Reason

Rationalism, promoted by Descartes, holds that the senses are not reliable sources of knowledge. Reason, dispensing with objective sensory input, recognizes absolutely secure and undeniable innate truths. Starting from these truths, one can discover authentic reality through pure reason.

Empiricism (Locke & Hume): Experience as the Limit

Empiricism, mainly represented by John Locke and David Hume, argues that human knowledge cannot transcend the limits of experience. For empiricists, there are no innate truths; reality is solely empirical and sensible.

Sensitive Knowledge and Perception

Sensitive knowledge is knowledge attained through the senses. Senses are powers that enable the direct perception of objects that are present and impress the cognitive subject.

Characteristics of Sensations

• Qualitative: Every sense always reacts the same way, regardless of the nature of the stimuli that impress it.
• Selective: Only a few stimuli around us—those within the upper and lower thresholds of each sensory organ—can produce sensations.
• Not an Exact Copy of Stimuli: The peculiarity of perceptual experience means that the environment, culture, and expectations of the individual influence sensations.
• Not the First Level of Knowledge: We do not first perceive qualities and then objects; rather, we perceive objects as wholes (more or less defined) and then analyze their qualities.

Laws of Perception (Gestalt Principles)

Perception tends to organize sensory input according to specific laws:

• Primacy of Wholes: Wholes are primary and take priority over the collection of their parts.
• Simplicity: Figures tend to be articulated in the most fully symmetrical and simple way possible, minimizing the energy expended by the subject.
• Constancy: Within certain limits, the perception of an object's size remains constant regardless of the subject's proximity or remoteness.
• Context: The perception of the same element can vary depending on its size relative to other parts of the whole.