For all (you) know

This phrase is used to contradict what someone knows, thinks or expects. It is used to emphasize a possibility that someone hasn’t thought of. It means that, “despite everything (someone) knows” there may be a factor that they haven’t considered. It introduces a new possibility or one not considered.

1. We’re planning a trip to the beach this weekend, but for all we know it could rain… so maybe we should look for some alternatives just in case. Maybe we could see the new 3D movie that’s coming out.

2.  It’s never a good idea to get married to someone you’ve just met recently or to meet someone online. For all you know that person could be a serial killer.

3. When watching movies, we usually make up our minds (decide) who the “bad guys” are very quickly. Sometimes things are not what they seem. For all we know, the “bad guys” could be working undercover.

4. When you are waiting for someone because they are late, you could think of all the worst case scenarios - all of the things that could have happened to someone along the way - but for all you know, they are probably just stuck in traffic.

5. Nat King Cole sang, “For all we know we may never meet again, Before you go make this moment sweet again, We won't say "Good night" until the last minute, I'll hold out my hand and my heart will be in it For all we know this may only be a dream, We come and go like a ripple on a stream.”

6. In many situations it’s easy to jump to conclusions and assume we know the answer or the reason to something based on limited knowledge, especially with what we think people are thinking. We could give people the benefit of the doubt and say, for example, “For all we know, he could be under the weather.”