In Praise of xkcd

When he was five years old, a little boy asked his mother if there were more hard things in the world, or soft things. His mother – entirely understandably – was a little non-plussed. The rest of the story is to be found in in the introduction to one of my all time favorite books, but for those of you who don’t yet have a copy of the book, his own answer to the question was that there were 3 billion soft things in the world, and 5 billion hard things.

That book that I spoke about – it’s called What If? – has this lovely little coda to that story:

They say there are no stupid questions. That’s obviously wrong; I think my question about hard and soft things, for example, is pretty stupid. But it turns out that trying to thoroughly answer a stupid question can take you to some pretty interesting places.

Munroe, Randall. What If?: Serious Scientific Answers to Absurd Hypothetical Questions . Hodder & Stoughton. Kindle Edition.

The book in question, by the way, invites you to ask some truly stupid questions, and then answers them entirely seriously. It is a rare ol’ treat, that book. To give you a sense of the kind of questions that the book tries to answer, consider my favorite example from the book:

Is it possible to build a jetpack using downward-firing machine guns?

Munroe, Randall. What If?: Serious Scientific Answers to Absurd Hypothetical Questions (p. 68). Hodder & Stoughton. Kindle Edition.

How do you not fall in love with a book that asks questions such as these, and answers them entirely seriously? How do you not admire a person who left his job with NASA (yup, seriously) to build a career based on answering questions such as these, and draw comics for a living? And how do you not admire the resulting blog?

The blog (and if you are learning about him and his blog for the first time while reading this blogpost, I truly envy you for the experience you are about to have) in question is, of course, xkcd. Click here for the answer to the inevitable question.

And what a blog it is. What. A. Blog.

Consider one that I love to use in some of my classes:

At first glance, you might think this to be a rather bland cartoon, and not funny at all. But don’t give up just yet, think about it for a minute. Take a look at the caption. That is your first clue.

This is an exam for a subject called cybersecurity. Which presumably means you have been taught how to hack into a server. So, if you want to pass this examination, your examination starts after you have been given a failing grade. To change the grade, you have to hack into those department servers, change your grade – and you have one day to do this.

Ah ok, you might say. Rather contrived, and still not really funny, but ok, I get it. But now for the coup de grace: most of the xkcd cartoons come with a caption. And the caption in this case is pure, unadulterated evil genius.

For those of you also taking Game Theory, your grade in that class will be based on how close your grade on this exam is to 80% of the average.

Let’s say you’ve learnt cybersecurity well enough to be able to hack into the server. Well done, you think to yourself. All I need to do now is give myself 100/100, and I’m done. But wait! What will your score be on the game theory exam? For you to know your grade on the game theory class, you have to know the average score on this exam.

That will be a function of three things:

  1. How many people have taken both classes?
  2. Of these, how many people have been able to hack into the server?
  3. Of these, how many people have learnt game theory well enough to figure it that it is not just about changing your own grade, but everybody else’s grade?

And it gets worse (better, really)! What grade are they likely to give everybody else and themselves? Folks who are familiar with game theory will recognize this to be a variant of the guess 2/3rd of the average problem. But with the additional tweaks mentioned above, and that’s what makes this problem such a fascinating one.

And this isn’t even my favorite xkcd cartoon! In fact, I wouldn’t even want to show you “my” favorites – please go ahead and spend time going through the blog yourself.

But if you want to learn something that is smart, funny, and thought-provoking all at once, you couldn’t do better than xkcd. Have fun!

Randall Munroe, thank you!

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