This is a placeholder to start the discussion of indivisibility, by first going back to why it was an issue for Epicurus in the first place. What questions or positions was he addressing?

Here are some starting points, first from David Sedley's "Lucretius and the Transformation of Greek Wisdom":

From the Cambridge Companion to Epicureanism, Epicurus was responding to Aristitotle's attacks on Atomism:

Here is where the issue of "movement" comes in, from the same source. We need more development of Epicurus' response to this. I am not going to have time to pursue this right now, but there had to have been important reasons for this dispute and we can't analyse the issue without uncovering them:

Godfrey: That is GREAT if you have time to tackle God and the Atom. I recall Alex saying many good things about Stenger and that book in particular. I think I scanned a few pages but that is as far as I got. It would be tremendously helpful if you are able to expand this or related threads with commentary from Stenger.

As far as the clips above those are from the Cambridge books so I don't think there is a full free copy on line.

I know I have read about this in various sources but unfortunately I don't seem to have kept good notes. That was one of the reasons for setting up this forum

Here's a clip from page 12 of DeWitt's book:

The whole issue of "infinity" is charged with implication, both down (infinite divisibility) and "up" (is it right to say that the universe is "infinite" in size, or is "boundless" perhaps a better word?) Because ultimately there must be no mystery to whether something exists or not.....

And of course those issues lead to the closing of the letter to Pythocles:

All these things, Pythocles, you must bear in mind; for thus you will escape in most things from superstition and will be enabled to understand what is akin to them. And most of all give yourself up to the study of the beginnings and of infinity and of the things akin to them, and also of the criteria of truth and of the feelings, and of the purpose for which we reason out these things. For these points when they are thoroughly studied will most easily enable you to understand the causes of the details. But those who have not thoroughly taken these things to heart could not rightly study them in themselves, nor have they made their own the reason for observing them.

Yes agreed that is part of the issue. If the word "atom" essentially means indivisible then you have an immediate definitional issue as to whether such a concept can exist. I am not well versed at all on these "ontological" issues -- such as does the fact that we can imagine a god (or an atom) itself mean that it '"exists."

I have to admit that I personally detest what I see as "word games" like I consider this to be. On the other hand, there is little doubt but that this kind of game-playing was rampant in ancient Greece (as it is today) and that Epicurus thought (and I think properly) that it is necessary to deal with it. If you are going to inoculate your school against infection by logic gamesmanship then you need a plan for response.

This thread really isn't off the ground yet and we're basically still brainstorming. We ought to identify and isolate the major threads of the argument and address them separately - once we have a handle on what they are.

Presumably the "plenum" argument is related to this as well, but I don't believe that the two issues are exactly the same, so that's an example of what needs to be split into pieces for analysis.

I bet you are correct Elayne at least in large part. There is also probably something going on here too that illustrates the limits of logic when not connected to observation. That might be the same thing, or might not.

It's apparently possible to construct a logic argument that motion is impossible. In contrast, we see and feel motion all the time. In such cases "logic" must give way to the senses.

Quote from Oscar

one of Zeno's paradoxes. This suggests that there are, supposedly, an infinite amount of steps to complete any distance, that it's hopelessly impossible because it can neither begin nor end. From this, the argument concludes that motion is an illusion.

Yes exactly thank you Oscar! Do you also have a short explanation of the problem with Zeno's argument ( other than walking across the room, which I gather is the standard and good! response?

Quote from JJElbert

Lucretius makes explicit the analogy that compounds of atoms are a kind of coded information, just as latin letters come together to form words. But in order for this to work out, there must be a finite library or alphabet of atomic 'letters'. If they could be infinitely divided, no such set would be possible. In this instance, infinity really does lead to zero.

Hmmmm. There is either a flaw in this reasoning, or it is an EXCELLENT observation and not one that I have personally seen before. Do those reading this agree that an alphabet must be finite in order to convey meaning? Is that what you are saying Joshua? If this argument holds up it is one that we definitely want to use over and over.

Does this go too far?

Quote from JJElbert

But in order for this to work out, there must be a finite library or alphabet of atomic 'letters'. If

Yes as to paragraph one.

As to paragraph two, I think you are correct two, Joshua. How could there be any confidence in the meaning of a word that was constructed of an alphabet for which there is no established list of symbols.

Now I guess what I am concerned about is the question of whether an alphabet could start off being a defined set but somehow expand without end, but since the expansion (it would seem) could not be agreed upon ahead of time then the result would surely be at least uncertain, if not totally meaningless.

I think the analogy is probably a very good one but I am looking to test it before reusing it. Since the root of it can be found in Lucretius it is an excellent suggestion.