An Epicurean Guide to Truth


This is my third post on Epicurus. If you’d like to read the first two, click here and here.

Like all philosophers, Epicurus was also obsessed with the idea of Truth (with the capital T). One of the great empirical questions that they teach you to ask in Philosophy 101 is this: ‘If a tree falls in a forest and there’s no one to hear it, does it still make a sound?’ We have no way of knowing whether Epicurus asked himself this question, but in his writings he gives enough indication to suggest that he’s a thorough empiricist.

He says there are three criteria for truth:

1. Preconceptions

These are notions that cannot be reduced further down by definitions. In order to be able to make sense of our surroundings, or to begin an inquiry into a school of thought, we need certain concepts that are universal: like ‘man’, ‘world’, ‘usefulness’, ‘truth’, ‘honesty’ and ‘justice’. Without these preconceptions, says Epicurus, every argument is liable to degenerate into a frenzy of definitions.

Just the other I asked a friend if she had ever been in love, and she sighed wistfully and said, ‘Ah, but what is love?’ Many of modern arguments, it seems to me, become hot and heavy primarily because the debating parties do not agree on the definition of terms. Or each party assumes that the opposition’s definition is the same as their own.

In his letter to Herodotus, Epicurus says:

In the first place, Herodotus, you must understand what it is that words denote, in order that by reference to this we may be in a position to test opinions, inquiries, or problems, so that our proofs may not run on untested ad infinitum, nor the terms we use be empty of meaning. For the primary signification of every term employed must be clearly seen, and ought to need no proving; this being necessary, if we are to have something to which the point at issue or the problem or the opinion before us can be referred.

Where do these preconceptions come from? From a combination of past sensory experience and an exercise of analogy and extrapolation that happens within our minds. From our past sensory experience of chairs, we know what one looks like, and we can engage meaningfully in a debate concerning whether armchairs or rocking chairs are more comfortable. But if we’d never seen a chair and have no preconceived image of it, will we be able to bring any value to the debate?

2. Sensations

These are physical inputs that we imbibe through our sensory organs. Colour, shape, size, sound, smell, taste, touch and texture. All information that we need to arrive at the truth, says Epicurus, is present in what our five senses give us. He insists that we should not hasten to judge our sensory information, that we must take time to assimilate it with a neutral air, as though a statistician would collect data.

In his Principal Doctrines, he speaks at length on this need to separate sensory input and opinion.

If you reject absolutely any single sensation without stopping to distinguish between opinion about things awaiting confirmation and that which is already confirmed to be present, whether in sensation or in feelings or in any application of intellect to the presentations, you will confuse the rest of your sensations by your groundless opinion and so you will reject every standard of truth. If in your ideas based upon opinion you hastily affirm as true all that awaits confirmation as well as that which does not, you will not avoid error, as you will be maintaining the entire basis for doubt in every judgment between correct and incorrect opinion.

Error, therefore, arises when we try to make judgments of our sensations and try to fit them into our preconceptions. When there is a conflict between a sensation and our preconceptions, we do one of two things: we reject the new sensation, or we change our preconceptions.

3. Feelings

Finally, what comes to be known as the Truth is a result of our feelings and judgments towards our sense inputs. Here’s where Epicurus cautions us that when new information arrives, our old preconceptions must be modified to suit, even though in practice, we get so emotionally wedded to our ideas that we resist change. He prescribes a healthy, rigorous form of skepticism to everything new, but once the ‘test is passed’, it must be included in our world view, and our previous models must be expanded to allow the new idea to fit.

Which ideas do we generally reject, and which do we accept? You would think that as a philosopher, Epicurus would appeal to our reason. But no. He implores us to make decisions based on the tools that Mother Nature has given us: those of pain and pleasure. What causes us pain is bad for us, and what causes us pleasure is good.

This ties his search for the truth to his ethical theory. For a more in-depth look into pleasure and pain, see this post.


  • Truth has three criteria to it: preconceptions, sensations and feelings.
  • Preconceptions are concepts that we store in our minds from past sensory experiences. Sensations are physical inputs that our sensory organs provide us. Feelings are what we use to make judgments of our sensations, and take decisions on whether we accept or reject them.
  • Ultimately, the arbiter of decision-making in human beings is based on whether the sensation causes pain or pleasure.


  1. R L Patnaik says:

    Sarat, Don’t you think this is what our Indian sages and philosophers have been propounding for the ages. Live a simple and desire-less life in absolute abandon. A life that is detached, which is achieved by contemplation and meditation. Looking inward by following the inner breath pattern. Unfulfilled desires bring pain and rob pleasure. What is ultimately the use of material riches when you don’t get that inner peace and pleasure. I never had an occasion to dwell the meaning and context of epicurean, except an occasional mention in the texts, that I never bothered to know. Thanks for this nice posting.


    • Hello, Mr Patnaik,

      Yes, we find similar strains of thought in different cultures. If anything, this is perhaps an indication of the fact that our paths may be different, but the goal is the same. We’re all trying to be happy, and we’re all trying to ‘figure it out’. We’re all searching for meaning.

      Thanks for the comment 🙂


  2. This is a good article, but note that this is the “standard” version of Preconceptions. Readers should be aware that Norman DeWitt’s version in his “Epicurus and His Philosophy” is much different than this as to preconceptions. The tipoff to the controversy is that, for the relevant part of the discussion, the writer here is clearly talking about forming observations from the senses into concepts, and using those concepts in the future. {“From our past sensory experience of chairs, we know what one looks like, and we can engage meaningfully in a debate concerning whether armchairs or rocking chairs are more comfortable. But if we’d never seen a chair and have no preconceived image of it, will we be able to bring any value to the debate?”}

    That process is what Dewitt would call “conceptual reasoning” and is all well and good. But note that the Epicurean term is PRE-conceptions. DeWitt argues (in my view persuasively) that the faculty of preconceptions provides INPUT into the conceptual reasoning process, but is not the conceptual reasoning process itself. This is a complicated subject with opinions on both sides as to what Epicurus meant, because the surviving texts are so fragmentary. But be aware when you read this that you’re reading the “Academic” view rather than something that is unanimously accepted and without controversy. I advise comparing and consulting Dewitt’s Chapter on the Canon of Truth in “Epicurus and His Philosophy” before accepting the version of Preconceptions described in this article.


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