As a sideline to the question How Long Did the Belief in the Egyptian Sun God Ra Last?, the comments have become a long discussion on the historicity of the Exodus. Rather than have pages of comments going back and forth, I have converted the sideline into the following question: what is the historical basis for the Exodus?
I admit, I never thought there was any question about the Exodus having taken place, but apparently in recent years the idea has arisen that it is just a myth or fable and did not actually occur. Some scholars have apparently felt impelled to weigh in defending the Exodus as history, for example Professor James Hoffmeier's Israel in Egypt: The Evidence for the Authenticity of the Exodus Tradition (1999). Books like 2002's "The Bible Unearthed: Archaeology's New Vision of Ancient Isreal and the Origin of Sacred Texts" present the case that the Exodus is a myth of some kind. The basic argument is that archaeological remains in ancient Israel do not show evidence of Egyptian culture, therefore, the Israelites could not have been of Egyptian origin.
The three major sources of the Exodus I know of: Bible, Manetho and Josephus, all seem to agree on the basic story. Also, it is a fact that Jerusalem underwent a large expansion around the time in question. Also, it is fact that Avaris existed and that it was abandoned around the time in question. Not conclusive, obviously, but the circumstantial evidence would seem to be strong. Also, my own experience with Manetho is that some of the data is garbled, but that archaeology has tended to ROUGHLY agree with it, so the idea that he just fabricated the Exodus, which is extensively described, seems unlikely to me. Also, Manetho was not Hebrew, so he would not have had any incentive to start fabricating origin myths for a "Canaanite" people.