Mastery of the contrapositive by an infant

On a New York sidewalk today I passed a stand selling baby outfits with this message printed in big letters across the chest,

“If I don’t sleep, nobody sleeps!”

We have here a fine case study in logic. The negatives on both sides are a tipoff that there’s a simpler equivalent formulation, the contrapositive,

“If somebody sleeps, I sleep!”

So why does this one feel so wrong? It’s the distinction between implication and causation. Yes, if somebody sleeps, that logically implies that baby must sleep. But it doesn’t cause baby to sleep, and indeed it’s baby who must drift off first before anyone else will get a chance. “If I don’t sleep…” says it right because it aligns the logic and the causation. Maybe it adds to the fun that we dimly sense this twist.

[29 September 2014]

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s