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Plato’s Dialectic

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Plato held that in philosophy, we arrive at the truth by means of a process of “dialectic.” Dialectic, for Plato, works as follows:

  • We begin by having one person put forward an answer to the problem in question on the basis of certain arguments.
  • Another person then comes along, points out flaws in the first person’s answer, and puts forward his own answer.
  • Then a third person comes along, criticizes both viewpoints, and puts forward an answer that is better than either of them.
  • etc.

Plato held that, over time, this process leads us closer and closer to the truth. This is illustrated by some of his dialogues.

Plato’s theory assumes that we have a way of rationally evaluating an answer to a philosophical question as plausible or implausible. Plato held that we could see this “intuitively,” but his account of intuition depends on his metaphysics, which most philosophers have rejected.

Another perspective on dialectic comes from David Hume. Hume agrees that it often happens in philosophy that one person puts a position forward, and then another person criticizes it and puts their own position forward. However, according to Hume, the intuitions that this process depends on are subjective products of “habit or custom.” So, while dialectic can arrive at conclusions that better appeal to a given person subjectively, it is not a source of objective truth like Plato thought.

I think the only way to answer Hume once and for all is to present a body of demonstrably true conclusions in philosophy. So long as philosophy is seen as an endless debate, many will be inclined to question whether it has any cognitive status at all. There have been a number of attempts to do this since Hume, and evaluating all of them is beyond my scope here.


Written by William

September 17, 2016 at 9:40 am

Introduction to Objectivist Epistemology: Chapter 1

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In this post, I will summarize chapter 1 of Ayn Rand’s book, Introduction to Objectivist Epistemology. This chapter describes the stages a child goes through leading up to the ability to use concepts, as well as the basis for those steps in reality.

According to Rand, there are three stages that a child goes through:

First, the stage of sensations. Rand suggests that “an infant’s sensory experience is an undifferentiated chaos” which is forgotten by the time one becomes an adult. Adults can infer that they once experienced a sensation stage, but they cannot bring a sensation into their conscious awareness.

Second, the stage of percepts. Rand says “a percept is a group of sensations automatically retained and integrated by the brain of a living organism.” Adults are consciously aware of percepts, and they form the level at which we are directly aware of reality.

At the perceptual level, the child attains the (implicit, not yet explicit) concept of an existent, a thing that exists. This implicit concept develops through three sub-stages: “entity,” referring to the objects around him or her, “identity,” referring to the fact that he or she can distinguish these entities from the other things he or she sees, and “unit,” which refers to the fact that there are similarities and differences between these objects’ identities.

Rand next spends some time on the concept “unit.”

A unit is an existent regarded as a separate member of a group of two or more similar members. (Two stones are two units; so are two square feet of ground, if regarded as distinct parts of a continuous stretch of ground.) … Units are things viewed by a consciousness in certain existing relationships.

Rand points out that this concept allows us to extrapolate beyond our observations by defining a standard and thinking in terms of repetitions of the standard. I think what she has in mind here is primarily physics; physicists define a specific distance as the meter and then do physics in terms of repetitions or divisions of that standard meter. The point applies to any concept, though. For example, we can recognize more than one country as instances of the concept “country” because we can abstract from the specific number of people in the population, the specific geographic location, the specific system of government, etc. These are essentially just repetitions of the same thing, or of similar things we have seen elsewhere.

Summary in bullet points:

  1. Sensation stage
  2. Perceptual stage
    1. Existent
    2. Entity
    3. Identity
  3. Unit (Entry to conceptual stage)

Written by William

August 15, 2015 at 4:05 pm

Introduction to Objectivist Epistemology: Forward

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Introduction to Objectivist Epistemology (ITOE) was Ayn Rand’s attempt to provide a foundation for her epistemology and, derivatively, the rest of her philosophy. In this post, I will summarize the forward of ITOE and comment on it.

In the forward, Rand repeatedly emphasizes the importance of the “problem of universals.” She takes the problem of universals to be the problem of what our concepts refer to in reality. For example, when I describe three men as “men,” what about those men am I referring to, if anything?

Why does Rand think that this problem is important? For one thing, since our knowledge is composed of concepts, the invalidity of concepts would entail the invalidity of all knowledge. If concepts are invalid, then there is no objective difference between mathematics and mysticism. She is probably also concerned about scientific methodology – if scientists don’t know where their concepts come from, then they might make conceptual mistakes without realizing it.

Rand lists four alleged solutions to the problem of universals that past philosophers have proposed: extreme realism, moderate realism, nominalism, conceptualism, and extreme nominalism. Rand expresses contempt for these solutions, but reminds the reader of the importance of the issue at stake for civilization.

It is worth noting that Rand introduces the problem of universals in roughly the same way the Internet Encyclopedia of Philosophy does:

Often we predicate properties of individuals. When we say that both cherries and rubies are red, for instance, we seem to say individuals share common properties, those that make cherries cherries, those that make rubies rubies, and those that make both red. Predicates are said of many subjects, then, but is there anything in reality to match the linguistic one-over-many? Are there general truths? Is there commonality in nature, in reality; or is commonality imagined and illusory, perhaps a mere product of language? If the latter, how can we accommodate the intuition that it is the world, and not our conventions, that make predications true or false? The Problem of Universals arises when we ask these questions. Attempts to solve this problem divide into three broad strategies: Realism, Nominalism, and Conceptualism. We’ll take these in turn, and consider the pros and cons of each.


Rand concludes by reminding the reader that she will be taking for granted the validity of the senses and the axiom that existence exists.

Written by William

August 15, 2015 at 11:58 am

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