Were the Lincoln-Douglas debates written down and simply read by the participants, or were both Lincoln and Douglas speaking extemporaneously the entire time?
I don’t know how much, if any, written notes the debaters used; but the text we have of the debates was taken down at the time by stenographers. From an interview with the man who edited the "most reliable, unedited record available of the debates ":
Decades ago I bought a copy of the full debates. The editor said that Lincoln’s words were taken from pro-Democrat publishers, and Douglas’s words were taken from pro-Republican publishers.
I read enough of the debates to be impressed with the very high quality of both candidates’ debating ability, even though I was reading text published by their opponents. If there was any distortion it was too subtle for me to notice. Of course I now cannot put my hand on the book but some googling might locate it.