This is actually obvious math to anyone who has actually watched our cat for more than a minute. More often than not he finds new ways of proving he isn't quite "with it". So for your review I will submit the following evidence....
Cat jumps off back of couch to get fly on wall on the cupboards. Failing to note that flys move frequently he lands head first into them at about 3 feet above ground and falls.
Most cats like to chase their tails, this is accepted. This cat likes to chase the shadow of his tail and gets upset when he can't catch it.
The cat likes chase the back of bags. The back of bags really. Anyway he will dive in head long into the bag and propell himself with his back feet until he hits a wall, again head first.
Signs of a stupid cat? I think so.