In contrast to his predecessors, Aristotle (384-322 BC) built his theory of knowledge on empiricism. The main principle of empiricism is that knowledge can only be gained from sensory experience before it can be assessed and refined.
Aristotle taught that humans start at birth with a blank mind (a blank slate) and will acquire knowledge through interactions with the external world.
In his early period (before 347 BC), Aristotle had endorsed Plato’s theory of innate knowledge. Plato had taught students that the human soul possesses innate knowledge drawn from a mystical world of pure abstractions. Learning, said Plato, is the same as remembering our innate knowledge.
By the time Aristotle opened his Lyceum in Athens to teach his own students (335 BC), he had discarded Plato’s doctrine of innate knowledge. I can only infer that Aristotle had regarded Plato’s theories as nonsense already for a long time, but that he only began to attack them when he felt financially secure.
In his book “Metaphysics,” Aristotle speaks of two broad categories of knowledge. He calls the first category “epistemic knowledge” and defines it as general knowledge and principles of general application. His second category is called “technical knowledge.” It includes detailed know-how and craftsmanship.
Syllogisms and Aristotle’s views on knowledge
How do you know if a statement is true or false? Aristotle answered this question by defining a logical method, which he named “syllogism.”
The Aristotelian syllogism is a deductive argument that is made of a major premise (“normally, the weather in Athens is warm in the summer”), a minor premise (“we are in the middle of July in Athens”), leading to a conclusion (“chances are that the weather will be warm today”).
In his “Metaphysics,” Aristotle also introduced the concepts of potentiality (“what an entity could become”) and actuality (“what an entity is”); He regards learning as the process of moving from potentiality to actuality. It’s the process of letting go of doubts and ascertaining the facts in detail.
According to Aristotle, every entity in the natural world has the potential of becoming a better version of itself; for humans, the potential is usually realized through learning and acquiring skills. Education is the process of developing one’s potential.
The acquisition of knowledge can be greatly facilitated and accelerated if we use precise vocabulary. To this end, Aristotle wrote the work “Categories,” where he defines key concepts in physics. The purpose of Aristotelian categories is to construct syllogisms with solid premises leading to flawless conclusions.
Aristotle didn’t build his theory of knowledge from scratch. He was well versed in the ideas of prior Greek philosophers, in particular Parmenides and Heraclitus, and took over their best concepts.
Aristotle’s views on knowledge compared to Parmenides’
Parmenides had lived in the fifth century BC, approximately one hundred years before Aristotle. He believed that the world is made of a single substance, and viewed multiplicity, changes and physical phenomena as illusions.
The doctrine of the whole world consisting of unique, single substance is called “monism” and does not make any sense. To his credit, Aristotle determinedly rejected Parmenides’ doctrine of the single substance.
According to Parmenides, our senses are deceptive because they are perceiving false multiplicity, changes and phenomena. In order to gain knowledge, Parmenides advised, we should let go of perceptions and use our reason.
Aristotle’s views on knowledge compared to Heraclitus’
Heraclitus was a contemporary of Parmenides, but came up with a philosophy diametrically opposed to monism. Instead of sustaining that the whole universe is made of an unchangeable, single substance, Heraclitus regarded the universe as devoid of unity and subject to perpetual change.
His most famous quotation is that “You cannot step twice in the same river” because the water is always flowing, always changing the river from moment to moment.
Since Heraclitus regarded change as the essential aspect of reality, he was sceptical of sensory perceptions. He considered our senses unable to provide stable knowledge in a constantly changing universe.
Nonetheless, Heraclitus believed that humans can grasp the unity and order of the cosmos by looking for principles (logos) behind the changing perceptions.
In his “Metaphysics,” Aristotle integrated the philosophical ideas from Parmenides and Heraclitus. He rejected the doctrine of monism (that the universe is made of a single substance) but came up with a single method for assessing reality, namely, by looking at the identity and causality of entities.
Aristotle also rejected the idea of constant change, but came up with the concepts of potentiality and actuality. Those enable us to differentiate the changeable and unchangeable features in events or entities.
The power of Aristotelian philosophy begins with its theory of knowledge. It’s the basis of civilization, science, technology, and governance. It is in your interest to become familiar with the key concepts identified by Aristotle in his works.
If you are interested in applying Aristotle’s ideas to solving everyday problems, I recommend you my book titled “The 10 principles of rational living.”
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