Folktheory, RobinZ, and I are designing exercises to go with the sequences. Here’s my first one. Please make suggestions as to how this could be improved or augmented and what to do the same/differently in future exercises. My current plan is to do more from the sequence "A Human's Guide to Words." This post will be edited to in response to suggestions.


Exercise for “The Parable of the Dagger," "The Parable of Hemlock," and "Words as Hidden Inferences

This exercise is meant to be worked on a computer. You can fill it out either in your head or by copying the text into a word processor. Please do not read ahead of where you are working. Where applicable, answers are posted in rot13.


1. List several properties which are common to crows. Here’s a picture of one to help you out:


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Some of the characteristics you may have put down are “black,” “bird,”  “can fly,” and “caws.”

People in the time of Aristotle believed things were logically 100% certain to have all the properties that were part of their definition. For instance, they said they could be 100% certain that Socrates was mortal because humans are mortal "by definition."

Now, thinking like an Aristotelian and using those four characteristics, is that bird in the linked picture a crow?

Answer: Lbh pna’g fnl jurgure vg vf be abg. Lbh unira’g frra vg syl be urneq vg pnj.


2. Now, suppose I (assume I’m completely trustworthy) were to tell you that there is a crow behind that door. If your brain worked like Aristotle thought, you would be certain that it had all the properties listed above. Think of two ways that you could be wrong.

Some possible answers:

Gur pebj pbhyq or n ungpuyvat, jvgubhg erq srnguref be gur novyvgl gb syl.

Vg pbhyq or na nyovab.

Vg pbhyq or obea zhgr.


If you were able to think of any of those answers, that shows you weren’t really certain. The fact that answers exist shows that it would be incorrect to be certain. If you were, and you looked behind the door and saw an albino crow, you either would have denied it was a crow, and been wrong, or you wouldn’t have been able to believe it was white. Assigning something zero probability means you can never update your beliefs no matter how much evidence you see.

Saying an object belongs in a category does not force it to conform to the attributes of the category.


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People in the time of Aristotle believed things were logically 100% certain to have all the properties that were part of their definition.

Surely not all people in the time of Aristotle believed that?

Let me amend it:

Aristotle and his disciples believed that things were logically 100% certain to have all the properties that were part of their definition.

From which we can of course conclude, by definition, that every disciple of Aristotle believed this proposition.

An advanced exercise would be to collect real world examples of when people ever make the mistake of thinking that categories can determine reality.

A medium-level exercise would be to find such an example, in some news article perhaps, quote it, and ask what is going on.

Could all of the Exercise posts be put into a sequence or (even better) somehow linked with the posts they are exercises for? I'm still working through the sequences, and I dont want to lose track of these posts before I even reach a point where I can do them.

Thanks for your suggestion. I linked this post in the comments of the three posts it's an exercise for, and put links to them in here. This post is also tagged "sequences_exercise", and future ones will be as well. I don't know what needs to be done to make exercise posts a sequence--is there anything besides putting them on the wiki sequences page?

Awesome :)


Thank you!

I worked the exercise and it was unclear whether “all the properties listed above” was to refer to the ones which I listed or the four which are given.

I would also suggest adding visual cues (such as a heavy horizontal line) for the boundaries to avoid reading ahead beyond (as opposed to 'seeing all of the current paragraph'), so that one can scroll down to the mark and not have to adjust further while reading. (Possible difference in experience: For me, it is quite hard to avoid skipping ahead in visible text, so 'not reading ahead' requires that I make the text invisible to me.)

I hereby commit to posting an exercise for "extensions and intensions" by Sunday, May 1. If I don't do it, downvote this comment to -10.


So... did you do it?

You, sir/madam, are a genius.

Thank you!

More wild applause from this corner. One suggestion: It's been a while since I read the corresponding posts, so I didn't really understand the Aristotle references. A short note in parentheses might be helpful.

Thank you for the applause. I intended this to be worked right after reading the post, but your idea of a brief explanation was good. I put one in.

I absolutely love this! The interactivity of the exercises helps me understand the material MUCH better than from reading alone.

I wish all the sequences had exercises. If anyone reading this comment feels like writing something, but doesn't know what to write, think of contributing some exercises. How awesome would it be for new people to LW if every couple of sequence posts, they could try things out for themselves?

When I finish with the sequences myself, I might try my own hand at creating some.