My roommate went out of town on Thursday. To celebrate, my subconsciousness decided to lock me out of the apartment by leaving my keys at home. Now this has happened to me a few times last summer. Luckily, we live on the first floor and our kitchen windows were unlocked, so I would simply climb back in. At some point, I decided that leaving windows unlocked on the first floor was not such a great idea and locked them. So there I was with no keys, no cell phone, and no roommate to let me back in. I tried a few of the windows just for the hell of it, but no luck. My landlady didn’t pick up. Long story short, I managed to call a locksmith who took half an hour to arrive and then informed me that he couldn’t open any of the doors because of the lock type. While standing there and pondering which one of my friends I was going to inconvenience tonight, I decided to try a living room window. Lo and behold, it opened. The locksmith charged me $75 (yep, just for telling me there was nothing he could do) and left.

Now the question is, should I leave some windows unlocked for next time? Sure, my roommate would probably not be out of town then. I will probably have my cell phone. But the probability of someone climbing in through an open window and robbing me is close to zero, as far as I can tell. The probability of me forgetting my keys is much much much larger. So if the probability of robbery is small enough and the unpleasantness of being locked out is large enough, I should be willing to leave a window unlocked.

The bigger point of this small story is that life is full of trade-offs. How much screening should we be doing at airports? What probability of an unfortunate event do we want to allow in order to avoid inconveniencing people? Many people I know would say that we’re currently going overboard. But there must be other people (who I don’t know) for whom no cost is too large to pay for security. But wouldn’t you be tempted to leave just one of the windows unlocked just in case you forget your keys again?

By the way, I also weighed the costs and benefits of writing this post + locking my windows + risking being locked out against not writing this post + leaving a window unlocked + not being locked out. You can clearly see my choice, so don’t even think about it 🙂