My Decision Theory

On my way to work I usually take a bus. Once, I’ve arrived to the bus stop a little bit late and had to wait for the next bus. I looked at the timetable and found out that the next bus was going to come in 12 minutes. I take two bus stops, which takes 4 minutes with the bus, or 20 minutes to walk.

I’ve decided to walk.

Now, mathematically, it was a wrong decision. Waiting for 12 minutes, then driving with the bus 4 minutes gives 16 minutes, which is shorter than 20 minutes. But, that day was very cold, so I’ve figured out I’d better walk and warm me up than staying at the bus stop for 12 minutes, possibly catching a cold. So, even if the decision was mathematically wrong, it was correct from the health point of view.

Several minutes into walking, I’ve watched a bus driving past me. What I’ve forgot while making my decision, is that two different bus lines pass my bus stop, and I can take both to come to work. I’ve looked up just one timetable and forgot about the second one.

As a consequence of this decision, I came into work several minutes later than I ought to come. Normally, this is not a very good thing. But I’ve worked a little bit more on the previous day, and I didn’t have any meetings scheduled, so that this hasn’t caused any major troubles. On the positive side, I’ve walked for 20 minutes, which was better for my health.

So, I took a decision, which was wrong both mathematically (16 minutes is less than 20) and logically (there was another bus line), but it didn’t have any major negative consequences, and indeed it was even good for my health.

Crazy, but this is how the world is. We take wrong decisions, but earn only positive consequences. Sometimes, we take perfectly correct and elegant decisions, that become huge source of negative consequences.

I’m still trying to understand how to handle it.

And this is by the way why I’m always laughing when I hear CS academics speaking about “reasoning about your code” and “formal proof of correctness”. They seem to be thinking, the biggest problem of software industry was to figure out, if 16 is less than 20.

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