If I knew, how to make a poll out of this, I would make it! (So, my tecnhical IQ is pure )
Thinking about the following criminal minds - among others - have this thing in common; Frank Morris, Robert Stroud (the most famous inhabitants of Alcatraz after Al Capone), Charles Manson (The Sharon Tate murders), Jeffrey Dahmer, Ted Bundy (notorius serial killers), etc.
So, do you think, that JtR fits with these criminals with his IQ?!
All the best
"When I know all about everything, I am old. And it's a very, very long way to go!"
I am not sure whether you are suggesting that the killers you listed had a higher or lower than avergae IQ (although I think you mean higher) but I would say that some serial killers have a higher than average IQs but are often under-achievers and poor scholars.
I would say that JtR's IQ would have been slightly higher than average but that does not mean that he was in a skilled trade or profession.
During Jack's day, IQ mattered little in terms of educational equality but certainly counted if you had to survive on the streets. At the time, little was known about what we call 'intelligence' and IQ tests as such were not available at the time of the Ripper murders. A chap called Francis Galton started the ball rolling and his work was extended and developed by his student, James Catell.
Traditional IQ tests are frowned on nowadays as it is realised that there are different types of intelligence and traditional ways of thinking about intelligence are not always helpful in delivering the right kind of learning to suit the person. Indeed, not everyone who is 'clever' in the traditional sense achieves their potential because it very much depends on who decides what that potential should include and how it should be measured.
What was jacks IQ? seems a question pretty much along the same lines as the "would we have liked mary kelly? george lusk? abberline?" threads which raised its head some while ago unanswerable and even if answered what would it matter? how intelligent would one have to be to kill 5 old tarts in 1888 whitechapel? IQ of an orange would have sufficed methinks