With regard to the Lucretius quote (and with the hope that Don might help with translations), I think maybe we would be well advised (today) to replace "certainty" with "reliance." What can we -- must we -- rely upon? And that, I think, Epicurus nailed (and, again, something that I suspect Sextus just misunderstood)
LOL! You know I'm always up for a good translation exercise, even in Latin. To which Lucretius quote are we referring?
I think he is pointing to brown translation here:
Lastly, if anyone thinks that he knows nothing, he cannot be sure that he knows this, when he confesses that he knows nothing at all. I shall avoid disputing with such a trifler, who perverts all things, and like a tumbler with his head prone to the earth, can go no otherwise than backwards. And yet allow that he knows this, I would ask (since he had nothing before to lead him into such a knowledge) whence he had the notion what it was to know, or not to know; what it was that gave him an idea of Truth or Falsehood, and what taught him to distinguish between doubt and certainty?
that would be around line 469
This is Bailey:
[469] Again, if any one thinks that nothing is known, he knows not whether that can be known either, since he admits that he knows nothing. Against him then I will refrain from joining issue, who plants himself with his head in the place of his feet. And yet were I to grant that he knows this too, yet I would ask this one question; since he has never before seen any truth in things, whence does he know what is knowing, and not knowing each in turn, what thing has begotten the concept of the true and the false, what thing has proved that the doubtful differs from the certain?
I think I understand and I do respect where you are coming from on "certainty" Pacatus. I think the question of wording has to depend on the audience we are addressing at a particular time, much as Don referenced in his recent post in this thread.
Due to the corruption of language there doesn't seem to be a way to get around the need to explain our terms pretty much no matter what term we use.
In this section of Lucretius there are no doubt various words that could be used to convey the intended meaning......
But the anxiety that the skeptics will have with these formulations will always be present too, and I am afraid that is a problem that can be improved with explanations, but can't be addressed by using the same words with all audiences. And if the skeptics cling to a P=1.0 requirement for holding that there is no hell -- and no doubt some will! - then I am afraid they are providing exactly the type of example of a self-limitation on happiness that Epicurus is warning against.
"You don't know there's no hell - and there's no way you can be certain - because you've never been there!"
Is that really a trump-card argument that should stymie an Epicurean into saying, "Well gee I guess you're right!" 
No I don't think so.
Nor is it sufficient as a general rule to say "We can never be sure of anything. Life is only a matter of probabilities." [Yes that's sufficient for those who are committed to be professional skeptics. I have to wonder how large a percentage of the world's population that is. I doubt it's 10% and it's probably a lot less.]
And if those aren't sufficient answers, and if Epicurean philosophy is open to and can be grasped by everyone who is of normal intelligence (as I think we all agree, which applies to everyone expect possibly very small children and those with true mental issues) then we have to be able to articulate an understandable theory of what it means to know something -- just as it appears the ancient Epicureans were doing in rebelling against Socrates/Plato and Pyrrho.
Caveat: My Latin knowledge (no pun intented) is slim to none, but I want to learn... so here goes.
Here is the pertinent section in English on Perseus (Leonard translation):
Lucretius, De Rerum Natura, BOOK IV, line 469
Same section in Latin:
Lucretius, De Rerum Natura, Liber Quartus, line 469
Pertinent word for knowing here is sciri. That's the word that is used throughout this section.
Charlton T. Lewis, Charles Short, A Latin Dictionary, scĭo
"In gen., to know, in the widest signif. of the word; to understand; perceive; to have knowledge of or skill in any thing, etc."
Here's a nice discussion on Stack Exchange on the difference between scio vs novi (and other "to know" verbs):
This is quite a large question, to which a comprehensive answer is easily found in the more comprehensive dictionaries under Know, with copious examples. However, in direct answer, there certainly are meanings not shared between the two, which I will try to summarise, although it is worth pointing out that the differences in usage can be very slight.
Scio is the most general word, meaning that you have a certainty, or at least clearly perceive, some fact(s) or other. It is followed by the kinds of clause that you would expect: acc. + inf., de + abl., relative + subj., neuter pronoun, and so on. Its opposite nescio, (‘not to know’, ‘be unaware/ignorant of’ etc.) is used similarly. But scio (and nescio) can also have the sense of ‘know how to …’ (particularly where it refers to a skill) as in scio scribere, nescio aratro uti.
The simple idea behind ‘not to know’ is expressed by ignoro (this being possibly more definite than nescio, which can be qualified by, for example, a clause after quin). The opppsite of ignoro is nosco, meaning ‘am acquainted with’, which is more usually seen in the perfect tenses, still giving a present sense in English. To claim a personal acquaintance, say, you might appropriately introduce yourself with te novi, or me no(ve)ris.
With, I think, a shade of meaning rather more active than that of simply learning (for which disco/didici or certior fieri is appropriate), the verb for the sense of ‘getting to know’ or ‘finding out’ is cognosco, most often in the perfect tenses to imply the knowledge for which scio in the present might sometimes be used equally well. Comperio is different again, with the sense of ‘know for certain’ or ‘tried and tested by experience’; compertum habet = ‘he knows without doubt’.
---- and -----
I would use novi (not scio) to mean to have met someone.
Notus is the participle of nosco and in a specific sense means acquaintance, friend (at least post-Classically, L&S only lists the plural noti in this sense). It seems to me that there is no parallel with scio for this meaning.
From the definitions, it seems that one can scire and noscere something, but only noscere someone.
I can find examples of novi+person, but none of scio+person without some deed by that person being the thing that is actually known.
As you can see, "knowing" is much more complicated than the English word would have us believe. The Romans split up the semantic field much finer when it came to knowledge it appears.
So for 'certain' we are talking "certo"?
"You don't know there's no hell - and there's no way you can know - because you've never been there!"
Where would this place called Hell be? My senses tell me there is nothing but atoms and void , and nothing is created from that which does not already exist.
You say "You've never been there." Again, I would ask "Where would I go to visit this place?" My senses and experience and reason tell me that there is no immortal soul that exists after I am dead. You say this "Hell" is a place of punishment potentially for me and for those who do evil in the world. But if I do not exist after I die - and I see no evidence that I do - how can this Hell-place affect me? Even if it does exist, who dwells in it? Spirits without bodies? And if they have bodies, where do they stand? If they are Spirit, they can have no effect on me now, while I am alive. And once I'm dead, I no longer exist for them to have an affect on me. If you say I've never there, you would be correct, because, to my understanding of the universe, there is no "there" to go to.
Probably the Latin for this jab from Cicero in "On The Nature of the Gods" is also going to be relevant:
Hereupon Velleius began, in the confident manner (I need not say) that is customary with Epicureans, afraid of nothing so much as lest he should appear to have doubts about anything. One would have supposed he had just come down from the assembly of the gods in the intermundane spaces of Epicurus!
I will see if i can find the Latin.....
Here it is: http://www.perseus.tufts.edu/hopper/text?do…%3Asection%3D18
18] Tum Velleius fidenter sane, ut solent isti, nihil tam verens quam ne dubitare aliqua de re videretur, tamquam modo ex deorum concilio et ex Epicuri intermundiis descendisset, “Audite” inquit “non futtilis commenticiasque sententias, non opificem aedificatoremque mundi Platonis de Timaeo deum, nec anum fatidicam Stoicorum Pronoeam, quam Latine licet Providentiam dicere, neque vero mundum ipsum animo et sensibus praeditum rutundum ardentem volubilem deum, portenta et miracula non disserentium philosophorum sed somniantium.
Interlinear translation: https://nodictionaries.com/novifex?text=1…et%2C+%E2%80%9C
So for 'certain' we are talking "certo"?
Yes.
Charlton T. Lewis, Charles Short, A Latin Dictionary, certus
determined, resolved, fixed, settled, purposed: non dubius.
Display MoreProbably the Latin for this jab from Cicero in "On The Nature of the Gods" is also going to be relevant:
Hereupon Velleius began, in the confident manner (I need not say) that is customary with Epicureans, afraid of nothing so much as lest he should appear to have doubts about anything. One would have supposed he had just come down from the assembly of the gods in the intermundane spaces of Epicurus!
I will see if i can find the Latin.....
Here it is: http://www.perseus.tufts.edu/hopper/text?do…%3Asection%3D18
18] Tum Velleius fidenter sane, ut solent isti, nihil tam verens quam ne dubitare aliqua de re videretur, tamquam modo ex deorum concilio et ex Epicuri intermundiis descendisset, “Audite” inquit “non futtilis commenticiasque sententias, non opificem aedificatoremque mundi Platonis de Timaeo deum, nec anum fatidicam Stoicorum Pronoeam, quam Latine licet Providentiam dicere, neque vero mundum ipsum animo et sensibus praeditum rutundum ardentem volubilem deum, portenta et miracula non disserentium philosophorum sed somniantium.
Interlinear translation: https://nodictionaries.com/novifex?text=1…et%2C+%E2%80%9C
M. Tullius Cicero, de Natura Deorum, LIBER PRIMUS, section 18
You beat me to it! 
Cross posted
Tum Velleius fidenter sane nihil tam verens quam ne dubitare aliqua de re videretur, tamquam modo ex deorum concilio et ex Epicuri intermundiis descendisset
Then Velleius confidently feared nothing so much as not to be seen to doubt about any matter, as if he had just descended from the council of the gods and from the interworlds of Epicurus.
And the youth might ask in reply: "And so, kind sir, are you telling me that all this adds up to your telling me that you are certain, and that you know, that there is no hell? Or are you trying to drown me in a sea of words and answer questions with questions and leave me unsatisfied like that gadfly Socrates?" 
You say "You've never been there." Again, I would ask "Where would I go to visit this place?" My senses and experience and reason tell me that there is no immortal soul that exists after I am dead. You say this "Hell" is a place of punishment potentially for me and for those who do evil in the world. But if I do not exist after I die - and I see no evidence that I do - how can this Hell-place affect me? Even if it does exist, who dwells in it? Spirits without bodies? And if they have bodies, where do they stand? If they are Spirit, they can have no effect on me now, while I am alive. And once I'm dead, I no longer exist for them to have an affect on me. If you say I've never there, you would be correct, because, to my understanding of the universe, there is no "there" to go to.
And the youth might ask in reply: "And so, kind sir, are you telling me that all this adds up to your telling me that you are certain, and that you know, that there is no hell? Or are you trying to drown me in a sea of words and answer questions with questions and leave me unsatisfied like that gadfly Socrates?
You say "You've never been there." Again, I would ask "Where would I go to visit this place?" My senses and experience and reason tell me that there is no immortal soul that exists after I am dead. You say this "Hell" is a place of punishment potentially for me and for those who do evil in the world. But if I do not exist after I die - and I see no evidence that I do - how can this Hell-place affect me? Even if it does exist, who dwells in it? Spirits without bodies? And if they have bodies, where do they stand? If they are Spirit, they can have no effect on me now, while I am alive. And once I'm dead, I no longer exist for them to have an affect on me. If you say I've never there, you would be correct, because, to my understanding of the universe, there is no "there" to go to.
I would simply turn the question back to you and ask you to define your terms when we speak of Hell. Describe this place of which you obviously have some knowledge that I do not possess. Please, tell me from whence you came about your certainty and where I, too, can gain knowledge of this place. I wish to learn!
We crossposted again and i added more:
Or are you trying to drown me in a sea of words and answer questions with questions and leave me unsatisfied like that gadfly Socrates?"
And the youth might ask in reply: "And so, kind sir, are you telling me that all this adds up to your telling me that you are certain, and that you know, that there is no hell? Or are you trying to drown me in a sea of words and answer questions with questions and leave me unsatisfied like that gadfly Socrates?"
Seriously though, if someone is going to ask me "Do you believe Hell exists?" I'd have to ask them what they mean by Hell. Not trying to be the jerk Socrates, but if they want to talk about Hell, what are they talking about and what gives them confidence that this place exists?
But if we're going to discuss it,...
Are we talking about an actual place of fire and brimstone inhabited by condemned souls existing after death in the Christian mythology?
I'd have to say that I have no reason to believe such a "place" exists in the universe other than in the context of Christian mythology. My experience of the universe demonstrates to me - to high degree of confidence - that there is no supernatural overlord - either benevolent or malicious - dealing out punishment. My experience also demonstrates to me that I am no more than my physical parts working in unison and out of that comes my consciousness. When I die, and my physical parts dissolve back into atoms and void, there's not going to be any thing - there will be no thing - which would or could be sent to a place like this Christian figment of the imagination.
Are we talking about a metaphorical concept of psychological punishment in the present? A "Hell on earth"? Okay, that's a more viable concept we can discuss.
And so on...
It's interesting to think about what terms to talk in. When Don says:
Are we talking about an actual place of fire and brimstone inhabited by condemned souls existing after death in the Christian mythology?
I'd have to say that I have no reason to believe such a "place" exists in the universe other than in the context of Christian mythology. My experience of the universe demonstrates to me - to high degree of confidence - that there is no supernatural overlord - either benevolent or malicious - dealing out punishment. My experience also demonstrates to me that I am no more than my physical parts working in unison and out of that comes my consciousness. When I die, and my physical parts dissolve back into atoms and void, there's not going to be any thing - there will be no thing - which would or could be sent to a place like this Christian figment of the imagination.
.... most reasonable people (98%?) are going to interpret that as as clear answer, and they are going to say to themselves and to each other (when talking about Don).... "Don is certain hell does not exist / Don takes the position that he knows that hell does not exist."
We as people sensitive to philosophical niceties shy away from terms like "know" and "are certain" because we don't like the philosophical sparring that goes along with those terms in philosophical contexts, But I would wager that most of the world does not think like that. And borrowing the terminology from Seneca they are looking to us for answers that they can understand, not riddles where we seem like we are evading giving a direct answer for reasons they cannot understand.
I think that's where Epicurus was willing to go considerably further than people in modern philosophical discussions are willing to go. He was standing up to Pyrrho and Socrates and he was willing to directly assert that it is possible to have confidence in knowledge and to say that indeed there are things that you "know" to be true -- even though you haven't been there or seen it for yourself. (When we think Epicurean confidence in atoms - which the Epicureans never saw or touched - it's kind of funny to be even having this discussion about taking firm positions on things we can't sense directly. Of course Epicureans were confident about things they had never experienced - and could never experience - except through indirect evidence!)
We're talking here in this thread in the abstract, and not about particular conversations with particular people. The context is going to determine the best wording. But the point of this thread, and the real point of the epicurean manner of argument it seems to me, is that it is possible to have confidence in the core conclusions of Epicurus and for Epicureans to say that they "know" that pleasure and pain are the ultimate guides, that there is no life after death, etc. etc. And in the proper context, even to say to ourselves or to other people that we are "certain" of them.
So, are you saying my response is too Socratic? To be more Epicurean someone should just say "I'm certain Hell doesn't exist"?
I suppose you could state that out of the gate then give reasons for it.
However, the question itself is nonsensical within an Epicurean worldview since Epicurus firmly stands on the conviction that "Death is nothing to us" since we are only this arrangement of atoms and void. We are material beings. Even if "Hell" existed, there could be no one - no things - to populate it. The concept of Christian Hell is built on a faulty foundation.
I suppose you could state that out of the gate then give reasons for it.
Yes I think that's generally the best way. Try to make a clear statement, and then explain it, rather than go from question to question to question as Socrates does in the Platonic dialogues.
I think partly I am analyzing this as a lawyer, where the rules of court generally are that the judge will sometimes tell the witness (when the question is appropriate) to "Answer yes or no, and then you can explain your answer...."
And partly I am trying to analyze this from an "ordinary person" standard, which is where we generally want to be proficient in talking (as opposed to talking within professional philosophy settings). We can't help normal people if they can't understand what we are talking about.
It's not a question of being more or less accurate, because it's possible to state the issue in understandable terms, as Lucretius does in Book 4. Or as Diogenes of Oinoanda does when he says that we admit that there is a flux, but it is no so fast that we are not able to comprehend it. Maybe the issue is one of "rhetoric" but that's another example of a word which has connotations that have overcome the word's usefulness.
It's certainly possible to debate the question of knowledge into oblivion, but I think Epicurus has his finger on a very practical problem. The "priests" succeed in their manipulations in many cases precisely because they have convinced normal people that the questions and answers are too complicated for them to understand. The only way out of that box is to begin to unwind the issues involved in what "understanding" is in the first place so that people can "resist the threats of the priests."
Fr. 5
[Others do not] explicitly [stigmatise] natural science as unnecessary, being ashamed to acknowledge [this], but use another means of discarding it. For, when they assert that things are inapprehensible, what else are they saying than that there is no need for us to pursue natural science? After all, who will choose to seek what he can never find?
Now Aristotle and those who hold the same Peripatetic views as Aristotle say that nothing is scientifically knowable, because things are continually in flux and, on account of the rapidity of the flux, evade our apprehension. We on the other hand acknowledge their flux, but not its being so rapid that the nature of each thing [is] at no time apprehensible by sense-perception. And indeed [in no way would the upholders of] the view under discussion have been able to say (and this is just what they do [maintain] that [at one time] this is [white] and this black, while [at another time] neither this is [white nor] that black, [if] they had not had [previous] knowledge of the nature of both white and black.
I've always liked this phrase in particular: "After all, who will choose to seek what he can never find?"
The goal of the priests is to discourage people from even questioning them, and they succeed when they convince people that no answers and no knowledge is even possible. If you can never know anything, never be sure of anything, never be certain of anything - then why bother questioning authority in the first place?
Question:
How does this conversation about certainty and "knowing" connect to the Epicurean position of waiting for evidence in matters with multiple potential, feasible causes?
Connects directly and in fascinating ways we need to explore! If the glove doesn't fit you must acquit!
We have to be able to identify when the evidence supports multiple causes, and when it supports only a single conclusion.
That seems to be directly the issue in PD24, which by reason of its inclusions in the doctrines indicates how important this issue was to Epicurus:
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.
It's definitely not easy to articulate this since we've been acclimated to the skeptical position that nothing is knowable, but it does all fit together when you think about it. You have to firmly identify in your mind the method, realize that you're not omniscient and this is the only real standard you have, and then not get shaken by arguments like "You can't be sure because you haven't been there."
I was thinking a few minutes ago, that's EXACTLY the implication in Cicero's jab at Velleius -- he's saying that since Velleius had NOT just come down from the Epicurean intermundia, he shouldn't be taking any firm positions on it.
Unless we firmly identify the fallacy in thinking that "you haven't been there so you don't know" invalidates every claim of knowledge, we never get anywhere.
I have never stuck my head in an oven and turned on the gas and lit a match but i am CERTAIN that that is not something that will benefit me from doing. And no amount of "you don't know because you haven't done it" will shake my confidence in that conclusion.
My OJ Simpson crack seems relevant too. In criminal law there's the "beyond a reasonable doubt" standard of proof, which is cryptically unwound to mean "a doubt for which you can give a reason."
On the other hand civil courts use the "preponderance of the evidence" or "more likely than not" standard.
And there's a lot of theory behind why one standard is appropriate in one context versus another, with "the need for finality" coming into play as maybe the ultimate reasoning behind having any standard at all.
So these are complicated issues but we deal with them every day and it makes sense to make it as clear as possible so that we can "affirm that which does not await confirmation" which maybe seems to be Epicurus' terminology.
Obviously we should wait before affirming a thing to be true when the evidence is inconclusive, and that's the part we are all comfortable with today.
But the rest of the story is that if we don't have good reason to wait before affirming an opinion to be true, then we shouldn't wait, seems to be the idea, especially when the issue is something important (supernatural gods, hell, heaven) which will have a direct impact on our enjoyment of life if we don't take a position.
