I stumbled upon this amazing video called "The Unreasonable Effectiveness of Dynamic Typing for Practical Programs"
It's about 50mins long and unfortunately vimeo has no fast playback options like youtube so I'd suggest you download it and view it in VLC then click Ctrl+ or Cmd+ to speed up
In any case he makes a very compelling argument that static typing isn't really all that. His argument is LOOK AT THE DATA!!! Everyone has opinions. People believe static typing catches bugs. People believe static typing helps document code. People believe static typing makes IDEs work better and therefore save time, etc. BUT ... those are all just beliefs not backed up by any data. He points out that so far all the studies suggest that's not true. He claims 5 years ago he was a static type believer but after looking up the research and doing some of his own he's convinced static typing is a net negative.
You should really watch the talk but I'll try to sum it up here