TITLE: My Lack of Common Sense
AUTHOR: Eugene Wallingford
DATE: August 27, 2012 12:53 PM
DESC: 
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BODY:
In high school, I worked after school doing light custodial work
for a local parochial school for a couple of years.  One summer,
a retired guy volunteered to lead me and a couple of other kids
doing maintenance projects at the school and church.

One afternoon, he found me in trying to loosen the lid on a paint
can using one of my building keys.  Yeah, that was stupid.  He
looked at me as if I were an alien, got a screwdriver, and opened
the can.

Later that summer, I overheard him talking to the secretary.  She
asked how I was working out, and he said something to the effect
of "nice kid, but he has no common sense".

That stung.  He was right, of course, but no one likes to be
thought of as not capable, or not very smart.  Especially someone
who likes to be someone who knows stuff.

I still remember that eavesdropped conversation after all these
years.  I knew just what he meant at the time, and I still do.
For many years I wondered, what was wrong with me?

It's true that I didn't have much common sense as a handyman back
then.  To be honest, I probably still don't.  I didn't have much
experience doing such projects before I took that job.  It's not
something I learned from my dad.  I'd never seen a bent key before,
at least not a sturdy house key or car key, and I guess it didn't
occur to me that one could bend.

The A student in me wondered why I hadn't deduced the error of my
ways from first principles.  As with
<A HREF="http://www.cs.uni.edu/~wallingf/blog/archives/monthly/2007-12.html#e2007-12-20T13_45_06.htm">
   the story of Zog</A>,
it was immediately obvious as soon as it was pointed out to me.
Explanation-based learning is for real.

Over time, though, I have learned to cut myself some slack.  Voltaire
was right:  Common sense is not so common.  These days, people often
say that to mean there are far too many people like me who don't have
the sense to come in out of the rain.  But,
<A HREF="http://en.wikipedia.org/wiki/Wikipedia:Common_sense_is_not_common">
   as the folks at Wikipedia recognize</A>,
that sentence can mean something else even more important.  Common
sense isn't shared whenever people have not had the same experiences,
or have not learned it some other way.

Maybe there are still some things that most of us can count on as
common, by virtue of living in a shared culture.  But I think we
generally overestimate how much of any given person's knowledge is
like that.  With an increasingly diverse culture, common experience
and common cultural exposure are even harder to come by.

That gentleman and secretary probably forgot about their conversation
within minutes, but the memory of his comment still stings a little.
I don't think I'd erase the memory, though, even if I could.  Every
so often, it reminds me not to expect my students to have too much
common sense about programs or proofs or programming languages or
computers.

Maybe they just haven't had the right experiences yet.  It's my job
to help them learn.
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