I split this off from the prolepsis thread thread as Don raises an issue I think is very important. I don't contend that I am sure of the right answer myself, so I think we need to flesh out even what the question means.
I think all of us as Don says are familiar with Plato having alleged that the senses are incapable of allowing us to attain truth, which exists only in ideal forms, and Aristotle being largely in the same place but saying "essences" exist in this world.
But Don has focused on whether Epicurus held that there is an "objective" truth:
While I agree "idealist truth" doesn't exist in the form of some Platonic ideal, truth as in the truth of existing things does exist. I would call that objective truth. The difference is "Is it true pigs exist?" Vs "Is it true that ice cream tastes good?" The first is the objective truth Epicurus was concerned with in using his Criteria. The second is subjective and contextual. If one starts questioning the truth of the existence of pigs, one rapidly devolves into a Socratic nightmare: "What do you mean by a 'pig'?" To my understanding, Epicurus stands on it being true that there is an objective reality with which we interact with our sensations.
What does it mean to say that there is an "objective truth?"
Is Epicurean canonics concerned with establishing "objective truth"?
I think there are some citations on this point that we can collect, and then of course there are many deep arguments that can be pursued.