you don't use an umbrella inside a building because you think the roof will keep you dry.
you don't call all your friends and family every minute to see if they're still alive.
you don't go take a crash course in (insert language you don't know here) because you believe you'll be able to speak the language you know to, say, buy food tomorrow.
what really happens? you get through your day, that's what.
you - we - make hundreds, thousands of assumptions unconsciously all day long (the pile above on the left). I would argue that we actually consciously think about a lot fewer things before proceeding (the few dots on the right).
but oh, just once, go ahead and assume when you should've checked something out and everyone's all over you for it!
just show them this chart and assume they'll get it.