• Postmortem / Debrief: after every project, a long conversation should take place where people review what happened, what assumptions were made, what went well and what could have gone better. 
• Experimental attitude:  “Let’s try working this way for a week and see what happens.” The continual exposure to the cycle of “assumption, test, learn, repeat” diminishes fear around asking questions and raises everyone’s comfort with making, challenging and testing assumptions.
• Discuss books about thinking: Are Your Lights On? is a favorite for inspiring people to think more critically, and humorously, about everything.

If you want to shift a culture the most effective way to do it is to change who you hire. 

It’s far easier to hire for traits you need than to try to transform a person who doesn’t have them into someone that does. The more people in an organization that successfully demonstrate a trait, t...