Dynamic versus Static Typing

People in the 1960s (such as Niklaus Wirth) pushed static typing in languages like Pascal. What evidence was there at that time that the lack of static typing was causing problems in software development? How many millions of lines of code, or how many software projects, did they look at to arrive at this assessment? (Yes, it’s a rhetorical question.)

So for the last four decades, we’ve lived with that static typing legacy, not ever questioning whether it was truly a good thing or not. And now we see anecdotal evidence from the Ruby and Smalltalk communities that perhaps static typing was not the great defensive facility that computer scientists made it out to be. Have we all been blinded by conventional wisdom?

Shouldn’t somebody make a detailed study of this question??