/r/askreddit lead me to the phantom time hypothesis, and I was hoping /r/AskHistorians could explain the history of the hypothesis to me.
I'm not really interested in a debunking of the theory, that seems simple enough. I'm more curious about the history of the theory. Who is Heribert Illig and why did he he want to believe it? Why would somebody subscribe to the hypothesis (both valid reasons for belief and reasons why that person would really want it to be true)? Is there anybody (or any group) who would benefit from people believing this hypothesis?
I have a followup question: if 613-911 never occurred, how does the Arab conquest and the expansion of Islam fit into these theorists historical timeline?
I'm no expert on this, but I dug into this area once when reading about Gary Kasparov's alleged support for the "Fomenko New Cronology", which is a somewhat similar theory originating in Russia in 1980.
Illig's theories need to be viewed in the context of a (strange!) set of theories originating from a man named Immanuel Velikovsky who published a book called "Worlds in Collision". This book is mostly about a set of (strange!) theories that are best understood as astrology.
My understanding is that the timeline for his astrology didn't quite work, so he concluded that the "traditional" timeline of history must be wrong.
Velikovsky's translator founded the "Society for the Reconstruction of Human and natural history", which Illig was later a member of.
There's also a set of work originating from the work of Jean Hardouin in the 1600s, where he claimed most Greek and Roman history was faked in the 2nd and 3rd centuries.
I'm not sure how much influence Hardouin had on Velikovsky (and Illig), though he did influence Fomenko.