In partial answer to Rolf and DaveT, my exhibit A on this issue, and I am sure there are many more when I go looking, is Lawrence Krauss and his "A Universe From Nothing," which I have referenced before as the subject of a video debate between Krauss and Richard Dawkins:
Quote from From Amazon ListingA Universe from Nothing: Why There Is Something Rather than Nothing Paperback – January 1, 2013
by Lawrence M. Krauss (Author), Richard Dawkins (Afterword)
https://m.media-amazon.com/images/I/81nt1V1DDcL._SY466_.jpg
Bestselling author and acclaimed physicist Lawrence Krauss offers a paradigm-shifting view of how everything that exists came to be in the first place.
“Where did the universe come from? What was there before it? What will the future bring? And finally, why is there something rather than nothing?”
One of the few prominent scientists today to have crossed the chasm between science and popular culture, Krauss describes the staggeringly beautiful experimental observations and mind-bending new theories that demonstrate not only can something arise from nothing, something will always arise from nothing. With a new preface about the significance of the discovery of the Higgs particle, A Universe from Nothing uses Krauss’s characteristic wry humor and wonderfully clear explanations to take us back to the beginning of the beginning, presenting the most recent evidence for how our universe evolved—and the implications for how it’s going to end.
(underlining added)
If this forum were dedicated only to the discussion among existing members, all of whom were well grounded in physics, the issue I am about to discuss would not be necessary to confront. But I don't think that "experts" were the main target of Epicurus, nor do I want this forum to require all discussion of physics to conform to the latest speculations of string theory or whatever is the fashion of the day.
Regular people need a coherent explanation of the nature of the universe that they can internalize and feel confident that the basics of a natural explanation are solid. We need not be able to reconstruct the universe ourselves just because atomism makes more sense than any other physics theory, we simply need one of more understandable frameworks of analysis that satisfies us that supernatural explanations are not required.
My reasoning behind the position I take is that ever since I took physics in college, and every year since then, I have been confronted with laymen arguments such as "Heisenberg's uncertainty principle" and "Schrödinger's cat" mean that the universe is ENTIRELY unpredictable, with the stated or unstated premise that as a result the preferred posture for an intelligent person is either total skepticism or return to supernaturalism.
I point to Lawrence Krauss' sensationalist book title, along with Richard Dawkins' perceived need to object on much the same grounds i am stating here, as just one of the recent examples of the same issue. My reading of Krauss' book is that he is fudging on what "nothing" really means, but he has structured his title and argument, as exemplified in the Youtube blurb, in a way that I perceive as entirely calculated to disrupt any confidence anyone might have in anything. Unless - that is - they hand themselves over to the physicist experts who allegedly have some esoteric knowledge that is unavailable to normal people, and in fact has in the past always been unavailable to anyone, from Leonardo da Vinci on down, without modern technological discoveries. The further implication is that we should consider ourselves fortunate we are to have such people as Krauss now to lift us to a new golden age, if we will only ask them how to live!
That attitude is bunk, but I think that's exactly what Epicurus was confronting in terms of the size of the sun arguments and the other assertions of the mathematicians and logicians of his own day.
The objections raised by Martin and Tau Phi are representative of good faith objections we have seen before and will see many times again.
I perceive Martin's concerns to be the standards of writing here at the forum -- that we not countenance the equivalent of flat earth theories that fly in the face of all evidence. I think most everyone here would agree with that, including me, but the kind of issues involved in the arguments of Krauss and others, which do in fact arrive back at Heraclitean indeterminacy, and which other highly-educated people are rebutting, are not in that category.
I perceive Tau Phi's concerns, which were also stated in our Zoom last night with more specificity, as being consistent with his more skeptical attitude that he freely states. The skeptical argument since before the time of Cicero to today is that is simply not necessary to take sides at all on any aspects of physics. I am sure he has a different take on his own position, but I would analogize his position to the position Frances Wright takes in "A Few Days In Athens" - she hardly mentions physics or necessity at all in her book, and to the extent she does mention it her statements are largely at odds with Epicurus' own. Her position in my reading amounts to the view that we should concern ourselves purely with ethics and not concern ourselves with infinity, eternality, or most anything outside the confines of the earth. In the end, Frances Wright's book, as brilliant as it is, did not lead to anything further for Epicurean philosophy, or for her personally (as far as I can tell), and that's what I perceive to be the reason why. Radical skepticism is ultimately totally unsatisfying, self-refuting, and leads nowhere.
I respect both Martin's and Tau Phi's viewpoints, they are friends of mine, and they bring much that is helpful to the forum. But Epicurus felt that it IS necessary to develop theories that oppose those of the radical skeptics and hard determinists and logicians -- even more than one theory if necessary -- and that IS necessary to be willing to draw conclusions on issues of ultimate concern to us. Is there life after death? Are there supernatural forces? Those questions cannot be EMPIRICALLY answered because we have not ourselves lived forever or observed everything in the universe, and anyone who proposes such a standard of certainty is on a fool's errand and asserting a standard that is both nonsensical and not something that they apply to other necessary day to day decisionmaking.
The question of "When is the evidence enough?" to justify reaching a conclusion is not one a physicist can answer -- not now, and not in another thousand years. And it makes no sense whatsover to conclude "we'll never know" so maybe we should hedge our bets and act as if there are supernatural forces and maybe our consciousness will survive death. There is plenty of evidence that contradicts those positions, and it is radical skepticism that both nonsensical, self-contradictory, and perverse to require us to apply that kind of standard of "certainty" to the most important questions of life.
Whether the ultimate particles are "hard" or "soft" or exactly why they "bounce" or exactly how they move are issues which will almost certainly not be determined in our lifetimes or ever. But what we already have, however, is reams of evidence that something like that DOES happen, and does support a general theory of ultimate particles. What we already have is amply sufficient to form a basis for explaining that the universe is natural in the face of those who insist that it is supernatural.
Coming to a close here, I believe Epicurus' point is that is the role of a practical philosophy to provide a framework for successful living. A large part of that framework requires a working theory that the universe is natural and operates regularly according to predictable principles. It cannot be accepted that a proper understanding of life requires a lifetime of dedication to abstract physics, nor can it be accepted that those who do devote their lives to such a pursuit are entitled to deference in every important conclusion of life - conclusions on which they themselves are divided and often attached to views that defy natural and ordinary experience.
That's why it makes sense to me to stay the course with Epicurus' strategy. Not every precise detail, but to his clearly-stated strategy of deducing reasonable conclusions based on available evidence.
To the extent possible we can and should explore the latest developments in physics and astronomy and everything else, and make sure that the latest discoveries ultimately can be reconciled with a natural order of things. But there is absolutely no reason to expect that this basically naturalistic viewpoint is going to be overturned tomorrow or in ten million years by viewpoints such as "everything flows" and therefore "nothing is unknowable." Those views were self-contradictory and absurd from the first moment they were asserted thousands of years ago, and they remain today and will remain forever self-contradictory and absurd.
We cannot be afraid not to be assertive on these points, even if we ourselves have not devoted our lives to the latest speculations in physics.