I would have turned the 5 card too. Why? Because it says to test the truth of the proposition. So it's saying all bets are off, whatever I told you may or may n

I would have turned the 5 card too. Why? Because it says to test the truth of the proposition. So it's saying all bets are off, whatever I told you may or may not be true. Only what you see (the table with the 4 cards) is real. If you still assume that each of which has a number on one side and a colored patch on the other side holds, then no need to check 5. But if you focus on testing the final proposition, I'm not sure anymore of what I should assume... Summary: poorly worded problem.