Issues In The Meaning And Definition of Logic

  • I think my best response to that would be to drop back and say that I think we should keep in mind the likelihood (I think a certainty) that Epicurus was aware of the need to, and constantly did, swap back and forth between talking in terms which are primarily "logical" at times, while at other times focusing on the "practical." I think he would say that doing so does not make him inconsistent but acknowledges the limits of logic (the need to always tie it to observable evidence) and the ultimate primacy of the canonical faculties given by nature.

    From this, and also from, I think, Episode 22 of the Lucretius podcast, that there is mention of "proper logic" or "proper reasoning", I remembered this podcast:

    Critical Reasoning: A Romp Through the Foothills of Logic | University of Oxford Podcasts - Audio and Video Lectures

    Which I have listened to, and can recommend. I like that she's very clear about logic being able to provide "valid" arguments, but not necessarilly "true" arguments, particularly that an argument can be valid but not necessarilly true. She does, however, make some distinctions about deductive logic and inductive logic that do have some prerequisites of truth or imply a high likelihood of truth for certain arguments, but I don't recall the specifics.

    Has anyone heard or read about her or this topic? I had never studied formal logic in school so this was completely new for me, and I think it, at least, allows you to order your ideas better while presenting an argument, which doesn't necessarilly imply a discussion.

    She also has this book about critical reasoning that I intend to read after finishing DRN:

    Critical Reasoning

  • I haven't had time to pursue this myself but I hope others will and also comment here.

    Also camotero as I mentioned a moment ago in another post you're going to want to add the appendix to the DeLacy Translation of Philodemus "On Methods of Inference" to your reading list. The appendix is excellent and compares and contrasts Epicurean views on these issues to those of Aristotle and Plato. After you read the appendix you're then equipped to begin to get something out of the text, which I think is hard to do unless you read the appendix first.

  • I like that she's very clear about logic being able to provide "valid" arguments, but not necessarilly "true" arguments, particularly that an argument can be valid but not necessarilly true.

    This is what has always struck me about logic (not that I'm close to being an expert!). You can have an internally consistent argument that has no basis in reality, so what's the point?

    Thanks for the podcast link, it looks interesting.

  • so what's the point?

    So what's the point?????

    Tsk Tsk Godfrey you will never be one of Plato's Golden and mesmerize the world with your incoerent gibberish!

    Unless you polish up on your geometry you will never figure out how to get the lower classes to defer to your every whim!

    I hope you wise up before it is too late!!!

    :) :) :) :)

  • I hadn't thought of it in this context, but over the years I've derived much pleasure from geometry, trigonometry and basic math. They have been pleasurable in themselves to varying degrees, and also as useful tools to realize the joys of drawings, which often themselves were useful tools in the creation of a variety of objects and spaces.

    In dealing with various theories of beauty and proportion, to me beauty and resonance in the resulting products invariably come down to the humanity and the feelings expressed. Without humanity and feelings, any coherent inner logic falls flat.

    Furthermore, I can't say that geometry, trig or math ever provided me with any valuable insights; they assisted in refining and communicating other, more interesting and relevant ideas.

  • I do think that math and geometry are useful and when not considered to be magical is valuable to know.

    I consider the issues involved in the recurrence of the Fibonacci ratio in nature to be fascinating and no doubt informative of something.

    So it's probably not just math and geometry that is useful for making oneself appear to be a wizard - just about any advanced knowledge can be employed that way with less-educated people.

    Meaning that there's certainly nothing intrinsically wrong with them but rather the use to which they can be out in the "wrong" hands

  • I find this link, that explains the different types of reasoning:

    Deductive Reasoning vs. Inductive Reasoning

    I think is short enough to be worth reading when you see this.

    This is sort of a very summarized version of what the podcast explains.

    This is what has always struck me about logic (not that I'm close to being an expert!). You can have an internally consistent argument that has no basis in reality, so what's the point?

    I'm not sure what internally consistent means, buy I gather that you may be talking about an argument being valid (that is, well formed) and it being true. This article addresses that: if the premises are false, the conclusion is going to be false. But this doesn't discard the whole framework of logic, as a useful means for communicating an argument, it just emphasizes that if you use it wrong you'll get wrong results.

    I do think that math and geometry are useful and when not considered to be magical is valuable to know.

    From what I read the only type of reasoning that would allow magic, is abductive reasoning, because it allows for the less certainty. As a understand them, deductive logic gives general premises to confirm that a particular case is an instance of them (less margin of error), the inductive takes particular observations to infer a general rule about things (more margin of error), and abductive takes whatever particular observations and jumps to "the most likely particular conclusion" (thus, the greatest margin of error).

  • Cassius

    Changed the title of the thread from “Logic” to “Issues in "Logic"”.
  • Thanks for the link Camotero!

    What I like about the descriptions in the linked article is that all three types of reasoning are discussed as part of the scientific method and subject to verification. What drives me crazy would appear to be deductive reasoning in which premisses are presented as true without proper examination. A particular conclusion is then accepted as true and used as a premiss for further argument. So as described in the article, proper examination and verification of each statement would lead to correct conclusions.

  • I need to check the texts but do I remember correctly that Epicurus didn't necessarily write against logic so much as rhetoric?

    I think the answer to that is once again "Logic" has to be defined. Saying that he attacked "all logic" is almost certainly overbroad. Lucretius talks about "true reason." The real target is probably better stated as "logic based on nothing that can be verified through the senses." Use of the term "abstractions" is probably overbroad, and "abstract logic" isn't clear enough.

    So I do think that Epicurus' target was definitely against more than "rhetoric" and there you have to consider his comments on poetry.

    The work "Against the Megarians" seems to be part of what we 're talking about.

    And you'll find what I am suggesting to be confirmed, with much more detail, in Delacy's comments to Philodemus including:

    Appendix 1 - Sources of Epicurean Empiricism

    Appendix 2 - Development of Epicurean Logic and Methodology

    Appendix 3 - Logical Controversies of the Stoics, Epicureans, and Skeptics

  • This first sentence from Diogenes Laertius taken out of context probably contributes people to being overbroad. And to add to the list above, a significant part of the target seems to be "Dialectical Logic"

    Logic they reject as misleading. For they say it is sufficient for physicists to be guided by what things say of themselves. Thus in The Canon Epicurus says that the tests of truth are the sensations and concepts [preconceptions / anticipations] and the feelings; the Epicureans add to these the intuitive apprehensions of the mind. And this he says himself too in the summary addressed to Herodotus and in the Principal Doctrines. For, he says, all sensation is irrational and does not admit of memory; for it is not set in motion by itself, nor when it is set in motion by something else, can it add to it or take from it. Nor is there anything which can refute the sensations. For a similar sensation cannot refute a similar because it is equivalent in validity, nor a dissimilar a dissimilar, for the objects of which they are the criteria are not the same; nor again can reason, for all reason is dependent upon sensations; nor can one sensation refute another, for we attend to them all alike. Again, the fact of apperception confirms the truth of the sensations. And seeing and hearing are as much facts as feeling pain. From this it follows that as regards the imperceptible we must draw inferences from phenomena. For all thoughts have their origin in sensations by means of coincidence and analogy and similarity and combination, reasoning too contributing something. And the visions of the insane and those in dreams are true, for they cause movement, and that which does not exist cannot cause movement.

  • Yep and then we have the question, "What is dialectic?" and it appears that's probably a reference to "dialectical logic" which also is probably a reference to the "Socratic method" or the methods used in Plato's Dialogs.

    I think there's also a relevant reference in On Ends when Torquatus begins his monologue and says that rather than question-answer he wants to use a narrative format. I think it's right before the section we usually start quoting:


    I quite agree with you, said Torquatus; for one cannot dispute at all without finding fault with your antagonist; but on the other hand you cannot dispute properly if you do so with ill-temper or with pertinacity. But, if you have no objection, I have an answer to make to these assertions of yours. Do you suppose, said I, that I should have said what I have said if I did not desire to hear what you had to say too? Would you like then, says he, that I should go through the whole theory of Epicurus, or that we should limit our present inquiry to pleasure by itself; which is what the whole of the present dispute relates to? We will do, said I, whichever you please. That then, said he, shall be my present course. I will explain one matter only, being the most important one. At another time I will discuss the question of natural philosophy; and I will prove to you the theory of the divergence of the atoms, and of the magnitude of the sun, and that Democritus committed many errors which were found fault with and corrected by Epicurus. At present, I will confine myself to pleasure; not that I am saying anything new, but still I will adduce arguments which I feel sure that even you yourself will approve of. Undoubtedly, said I, I will not be obstinate; and I will willingly agree with you if you will only prove your assertions to my satisfaction. I will prove them, said he, provided only that you are as impartial as you profess yourself: but I would rather employ a connected discourse than keep on asking or being asked questions. As you please, said I.

  • And of course there is this from the Letter to Herodotus, and I think the key to the point is in the last sentence, and not in the direction that some apparently took to think that there was a picture-based "fourth leg" of the canon. Reasoning based on words that ultimately have no way to be checked back against the canonical faculties are the main danger, I think, but that takes a lot of explanation too:


    First of all, Herodotus, we must grasp the ideas attached to words, in order that we may be able to refer to them and so to judge the inferences of opinion or problems of investigation or reflection, so that we may not either leave everything uncertain and go on explaining to infinity or use words devoid of meaning.

    [38] For this purpose it is essential that the first mental image associated with each word should be regarded, and that there should be no need of explanation, if we are really to have a standard to which to refer a problem of investigation or reflection or a mental inference. And besides we must keep all our investigations in accord with our sensations, and in particular with the immediate apprehensions whether of the mind or of any one of the instruments of judgment, and likewise in accord with the feelings existing in us, in order that we may have indications whereby we may judge both the problem of sense perception and the unseen.

  • I would really like to dig into what this means here, as I think this is where people go wrong and think that there's something mystical about the "first mental image" reference. As I read them they are thinking that "concepts" formed in our mind after reflection (such as are described by Diogenes Laertius in his statement of preconceptions) become primary evidence of truth. I do not think Epicurus would agree with that, and I think I would argue that all concepts are essentially "words" - they are the map and not the terrain and can never be confused with the reality itself. I think he would argue that words can never fully describe reality, and that "reality" is what is given to us by the pre-rational faculties (including not only the five senses but also by (2) pleasure and pain and (3) the non-idea-based anticipations):


    For this purpose it is essential that the first mental image associated with each word should be regarded,

  • Quote

    [38] For this purpose it is essential that the first mental image associated with each word should be regarded,

    As I see it the key issue would also include whether this "first mental image associated with each word" functions automatically or consciously/rationally, because if it is consciously/rationally assigned then that involved (in my view) the injection of opinion and the possibility of error, and that's the point in the process where error is made. If we accept a word/concept as something that is given to us by nature and that we processed involuntarily, without reason/opinion, then we've just injected into our canon of what is supposed to be "truth" our own opinion. And then once you consider your own opinions to be canonical, you're going to consider them as equal to "seeing is believing" and you're going to do exactly what Epicurus warned against in losing your true standard of judgment:


    PD24. If you reject any single sensation, and fail to distinguish between the conclusion of opinion, as to the appearance awaiting confirmation, and that which is actually given by the sensation or feeling, or each intuitive apprehension of the mind, you will confound all other sensations, as well, with the same groundless opinion, so that you will reject every standard of judgment. And if among the mental images created by your opinion you affirm both that which awaits confirmation, and that which does not, you will not escape error, since you will have preserved the whole cause of doubt in every judgment between what is right and what is wrong.