This is a phrase my brother, a former captain in the Marine Corps, likes a lot— and it’s one the military uses frequently. What this maxim does is turn the somewhat fatalistic “Murphy’s law” (“Whatever can go wrong, will go wrong”) into something that you can do something about.

Why am I obsessed with this right now? Well, I’m on my way to Las Vegas on Saturday to give an enormous presentation. Making sure it goes flawlessly is job #1 around here right now.

At its most basic, however, Two is One and One is None is about making sure you put two pens into your pocket before your meeting – saving you the embarrassment of breaking out your legal pad prepared to take careful notes, and then having to say, “Um…my pen seems to be out of ink.  May I please borrow one?”

Because the truth is, pens fail; white shirts get spilled on (experienced consultants always pack an extra on overnight trips) and important papers get mislaid.  If, however, before setting out for an important event, you think, “Two is one, one is none”, you’re less likely to be caught out when Murphy’s Law strikes.

Looked at another way, when you go into a meeting or an interview or a lunch, it reminds you that you need to have thought through at least two options for each choice you’ve made—from the answers to the questions you might get to the possibilities for entrées you might order. In every case, knowing you have ‘built out’ beyond Plans A and B to Plan C is going to give you an enormous amount of mental comfort.

Which is why I will be taking my presentation on my computer, putting it on an external drive, posting it to an FTP server for a colleague to download and putting my FedEx account number on speed dial in case a copy needs to get to the hotel overnight.

If all of this seems a bit over the top, or [some might say] paranoid, consider another favorite expression of my brother’s—courtesy of Henry Kissinger– which I’ve also found useful from time to time: “Paranoid is well informed.”