I'm reading the introduction of Voula Tsouna's "The Ethics of Philodemus" (published in 2007)and found this regarding their fragmentary nature:
QuoteAs mentioned, I have kept down the technical aspects of Philodemus’ texts and have treated them as philosophical writings to the extent that this is possible. However, there are limitations to that effort which are set by the peculiar nature of the evidence and, especially, by the fact that many passages are fragmentary, and their restorations partly conjectural. I have tried to avoid the phenomenon that David Sedley was the first to characterize as ‘bracket blindness’: i.e., the tendency to overlook the brackets surrounding editorial restorations of a word or passage and thus develop interpretations based on slim or even non-existent evidence. But sometimes I have taken the liberty to interpret heavily supplemented passages when the interpretation that I propose finds support in the context.
I have used square brackets in my translations to indicate those places in which a given passage has been heavily restored, and hence its translation and interpretation are largely conjectural. On the other hand, I have not marked with square brackets supplementations where I have a high degree of confidence in their correctness. Overall, I have indicated that not everything in Philodemus is at the same level of certainty, and, moreover, I have demarcated places in which the evidence is particularly precarious. But I have not undertaken to show systematically here the special difficulties and pleasures of working with the texts of the Herculaneum papyri, although I hope that I have conveyed to my readers some sense of that too.