The Discourses, a work attributed to the ancient Stoic philosopher Epictetus, is believed to have been compiled from Epictetusʼs lectures by his student Arrian.
Conclusion
That is highly unlikely. rephrased: It's very unlikely that Arrian, the student, wrote The Discourses and then falsely attributed the work to his teacher Epictetus.
Intermediate Conclusion
If Arrian tried to pass off his own views as Epictetus's, this deception would soon be exposed.
Evidence
Epictetus' views were well known by his contemporaries in Roman society.
Evaluate
Some people think that The Discourses was Epictetus's thoughts (via academic lecturers) that were compiled by Arrian; other think that Arrian just wrote it himself.
The author finds that 2nd hypothesis very implausible, so to strengthen her argument we want to either make it seem more like Epictetus really is the source of the material in the book, or that Arrian did not write it, or both.
If we were opposing counsel, we'd be trying to defend the idea that Arrian did write. The author is saying, . What could opposing counsel say?
- Maybe Arrian didn't realize that people would figure it out; Arrian thought he could get away with it.
- Maybe Arrian wrote the book but never wrote his name on it, and someone else came along and assumed it was Epictetus
- Maybe Arrian knew people would figure out the deception but didn't care because he either likes pranking people or knew he would be dead or out-of-town by the time people figured it out.
- Maybe the views in the book aren't related to the well-known views of Epictetus. Perhaps they're on a topic not previously addressed by Epictetus. Thus, there would be no basis for people noticing a mismatch between what they knew to be Epictetus's view on a matter and what view this book was attributing to Epictetus.
- Maybe Arrian's views actually aligned so much with Epictetus' that no one reading the book who already knew Epictetus's views would find anything that seemed noticeably different.
Goal
We want to rule out any of these potential objections (e.g. we want to hear / "Arrian did have different views from Epictetus and this book did cover topics for which it was already well-known what Epictetus' views were).
Or we just want any new fact that makes it more likely that Arrian would not have written this book or would not have tried to fool people into thinking that Epictetus wrote the book.