"On Methods of Inference": Notes For Review And Discussion (Including David Sedley Article: "On Signs")

  • (Note: these are my personal notes. Not all of these notes are from the book; some are from Google to help me further understand the basic ideas, and some are my"notes to self".)


    Signs: what you see or what you think about


    "All instruction is either about things or about signs; but things are learnt by means of signs. I now use the word “thing” in a strict sense, to signify that which is never employed as a sign of anything else: for example, wood, stone, cattle, and other things of that kind. Not, however, the wood which we read Moses cast into the bitter waters to make them sweet, nor the stone which Jacob used as a pillow, nor the ram which Abraham offered up instead of his son; for these, though they are things, are also signs of other things. There are signs of another kind, those which are never employed except as signs: for example, words. No one uses words except as signs of something else; and hence may be understood what I call signs: those things, to wit, which are used to indicate something else. Accordingly, every sign is also a thing; for what is not a thing is nothing at all. Every thing, however, is not also a sign. And so, in regard to this distinction between things and signs, I shall, when I speak of things, speak in such a way that even if some of them may be used as signs also, that will not interfere with the division of the subject according to which I am to discuss things first and signs afterwards. But we must carefully remember that what we have now to consider about things is what they are in themselves, not what other things they are signs of. AUGUSTINE, De Doctrina 1.2." From the Heidlblog


    Chapter 2, Introduction to Philodemus On Methods of Inference

    Per the Stoics:

    - Common sign: exists whether the unperceived object that it signifies exists or not. Therefore not a reliable basis of inference.

    - Particular sign: exists only when the unperceived object that it signifies exists. If the existence of the object signified is denied, then the existence of the sign must be denied as well. These provide the only reliable grounds for inference and are established through the purely formal test of contraposition.

    - Contraposition: inference from a logically equivalent contrapositive.

    - Contrapositive: "if not-B then not-A" is the contrapositive of "if A then B."


    Per the Epicureans:

    - The relation between sign and thing signified is learned only through perception, through the method of induction or analogy. We infer the nature of unperceived objects by analogy with the objects in our own experience.

    - Inductive reasoning makes broad generalizations from specific observations; aims at developing a theory.

    - Deductive reasoning works from general to specific; aims at testing a theory.

    - If a constant connection between objects is not first established by perception, contraposition is impossible.

    - Epicureans use inductive reasoning, and agree that common signs are not a valid basis of inference.

    - Inconceivability, not logical necessity, is a criterion of a particular sign and is based on past experience. An inference from signs is valid if it is inconceivable that the sign exists when the thing signified does not. (page14) (Hmmm. What are some examples of this? )

    - The four empirical criteria of truth: perception, anticipation, mental perception and feeling. Mental perception is defended and used in reference to knowledge of the gods.

  • There are signs of another kind, those which are never employed except as signs: for example, words.

    So in many instances in Philodemus when he is talking about signs he may in fact referring to "words"?


    It seems to me that "signs" is very ambiguous to most people in this context and we really are going to have to see if we can agree on and emphasize a clear definition here.


    Godfrey are your references from chapter two quotes, or your own summaries?


    The information you included in that post seems highly helpful and very important, but I am not yet shaking the feeling that a lot more is going to be needed to make the points clear. "Contraposition" might actually be easier to understand because we don't have a preconceived notion of what that means. But "sign" is a word we think we understand, and it seems to be used here in a very technical sense that is going to be easy to confuse. If I recall OMOI is full of sentences using the word 'sign' so it would really be nice if we could articulate something that would get people comfortable with use of the word "sign" in a context like what they are going to read.


    I have no feel for whether the Augustine quote is accurate or trustworthy or not, but I do think that an elaboration and explanation like he is giving there (but maybe considerably longer) is what is needed.

  • Accordingly, every sign is also a thing; for what is not a thing is nothing at all. Every thing, however, is not also a sign.

    This would appear to be a very critically important assertion if it is in fact an accurate representation of the position that Philodemus is taking, but I have no clue how reliable this statement should be considered to be. Is this in fact an accurate summary of the way (1) philosophers in general, and (2) Philodemus, think? I immediately worry that this conclusion may be "begging the question" and assuming a position with which Philodemus may not agree.


    Do we know for sure that Philodemus would agree with this?

  • Godfrey are your references from chapter two quotes, or your own summaries?

    Some of these direct quotes but most are my paraphrases. Also I've included definitions from other sources to try to make sense of the DeLacey commentary. This is all out of my wheelhouse and the terminology is new to me; these notes are literally my attempt to read and make sense of this material. Hopefully it's of some value but it's definitely not "gospel!" ;)


    I agree that a lot more information is needed to make the subject clear. This material is dense and extremely confusing for a novice such as myself. As you point out Cassius it's difficult to understand what is meant by "signs," and that seems to be the most basic idea involved! Hopefully the additional papers will bring some clarity.

  • You're seeing exactly what I saw Godfrey. Even now I'm not sure what to make of the terminology. Maybe the Sedley article Don found above will help us all.


    Is the reference above to "On Signs" the same as "On Methods of Inference"? It would seem likely but I haven't verified that, so it's interesting if DeLacy has already "translated" the title for us.

  • Good grief. So according to Sedley there is a second edition of DeLacey's translation of Philodemus on Signs. I don't see that listed anywhere though --



    Presumably that won't change his commentary much but I sure would like to see the updated text.

  • This seems sort of clear. The Epicurans followed analogy and induction. (I remember DeWitt saying they use deduction too.)


    The Stoics follow "elimination" method, which I presume is what is referred to in "contraposition"?


  • Yes I reall DeLacey talks a lot about inconceivability and this makes sense to me as an "empirical" rather than logical test:




    In fact it also may hark back to our discussions elsewhere on the "feeling" of certainty.

  • Probably a very important summary of the Epicurean position that our opinions should be based on observation and experience and not on "pure logic"


  • http://wiki.epicurism.info/Philodemus/

    According to this, there are at least 3 books in On Signs and Methods of Inference contained in PHerc 1065.

    It also lists On Methods of Inference (1978)

    Is Delacy a full translation of PHerc 1065?

    I'd suggest we take a closer look at the paper by Manetti.


    PS According to chapter 2 of Delacy, his work does appear to be a translation of PHerc 1065. If you read that chapter, it also seems to allude to the On Signs alternative title.

  • At this moment I am rushing to finish David Sedley's article to see if I am going to be forever struck-through-the heart disappointed in him, or whether he basically agrees with DeLacey's point I keep underlining. I am sure there was and is a lot of pressure on him to go with the Stoic/Platonic position.

  • Yes this is really the whole ball of wax. The Platonist /Stoics are playing "word games." They are asserting that by means of incantations -- If this, then that - and similar syllogistic reasoning they can deduce "universals" that they attach a truly mystical significance too, and the Epicureans were fighting all the way against that. Our wishes and our words do not create reality -- reality is reality, and we simply do the best we can to describe it in words. There are no "forms" or "ideas" or "concepts" floating in the air waiting for us to discover them.