Cartesian beliefs on sensory perception vs Epicurean knowledge acquired through the senses

Profkesarsarwara - Great to hear from you and that you are studying philosophy so closely! Your father would be proud!

The short answer to your question is that there is a flaw in the premises that the senses are ever deceived. The senses do not form opinions, they simply report information exactly as they perceive it. Opinions are formed in the mind, and it is there that error takes place if we conclude something that is not sufficiently supported by clear and repeated observations of the senses. Erroneous opinions cannot be corrected if the information from new sensations is not accepted with the same confidence as those of prior perceptions, so if is false to deride the senses as unreliable. It is the proper use of the senses that is in question, and so all opinions have to be tested against repeated observations of the senses and nothing accepted as true unless and until the observations begin to line up consistently with one another.

A longer presentation of this can be found in Book 4 of Lucretius where this precise issue of illusions is discussed. (I will come back and post a line reference)

I also highly recommend the entirety of Chapter 8 of DeWitt's "Epicurus and His Philosophy," especially that part from the start of the chapter up to page 142.

Check your messages here and I will respond further, but this should get you or anyone else started on the path that makes tne most sense to me in interpreting Epicurus on this issue.

Some others might have better responses on this, but my first thought is that some point you are going to run into your question being a matter of biology rather than philosophy. Philosophically, the issue divides between the mind (whatever that is) and the eyes (for example, whatever that is) and the formation of opinions. Philosophy isn't going to be able to tell you the exact mechanism of these things, but when you are asking mental questions about whether to trust "the senses" or "something else" or "nothing at all" then you into philosophical choices. Reductionism to worrying about what particular atoms are doing at a particular moment is impossible and self-defeating and not required in order to come up with a logical framework of analysis. I think Epicurus was mostly concerned with answering those from a philosophical perspective who asserted that "the senses can't be trusted" but on the other hand "reason" or "logic" or "the gods" can be trusted. Epicurus is pointing out that those alternatives do not really exist, in that the gods don't answer these questions for you, and "logic" and "reason" do not have direct connections with reality to answer them either. Only the senses (and anticipations and feelings) are considered to be direct connections with reality whose input must be dealt with as "real."

Also as to this

Quote from profkesarsarwara

I hadn't considered the mind and the senses as being separate, and error in the former being caused by lack of information from the latter

It would probably be better to say that the mind and the senses are separate, and that errors in the mind are caused by misinterpretation by the mind of the information provided by the senses. The senses report "truly" exactly what they perceive, without any added opinion. Exactly what to make of what they receive, however, is the job of the mind, and the mind very easily jumps to conclusions that are not warranted by specific perceptions of the senses. The only way to judge the 'truth" of an opinion generated from one set of observations is to test it by the opinions generated by many other observations over time and from various perspectives. Only when the assembled opinions start to resolve into a consistent conclusion are we confident that the opinion is correct. So sometimes "lack of information" would be the right term, but probably a better way of looking at it is that the observations over time are not consistent, so we need to suspect that something is going on to cause us to want to "wait" to form a strong opinion until the observations begin to resolve consistently with observations about which we are confident.

Also - I had forgotten that Joshua had brought up this very issue - of Descartes - in our recording of the Lucretius Today podcast two days ago. It isn't quite ready for release but when it is I will come back here and point out how Joshua addresses this around the 40 minute mark.

Profkesarsarwara -- The new podcast is up (see the link at the top of the past) and we start treating the evidence of the senses argument around the 38 minute mark.