There are a few paradoxes surrounding the general concept of intelligence. Most of them are academic constructs, making no notable points. I've listed a couple here. The second one is a good take-away, and possibly something to reflect on as we go about building our lives following markers that society defines as measures of intelligence and success.
1. The un-PC paradox: Yes, I've named it myself. It's a throwback to a pet topic, Darwin's theory of evolution. Ideally, as we tend to infinite time, the selected random mutations in our DNA should make us supermen. This conceivably includes our becoming super-intelligent as well. The paradox however is in the reality of our times, economic and social. Those of our species considered to be elitely intelligent tend to have way fewer children than the lesser-blessed crowd. These are raw statistics. The intelligence gene pool is skewed towards devolution. Random dna mutations vs a lesser number of intelligent pro-creators.
And then there's
2. The intelligent life -
Society pushes the more intelligent beings of our species to take up jobs that demand they use this intelligence to the fullest capacity. As a result, an intelligent person ends up becoming a lawyer juggling five corporate cases, or an investment banker paying meticulous attention to her commas and zeroes. This leaves them with fewer mental cycles to exercise their intelligence for themselves, having sold most of it off to the highest bidder.
The blue-collar joe then becomes today's thinker. A big step for joe, a smaller step for mankind.
As a result, the sum total of our intelligence is hard-pressed to grow. Call it the devolution of intelligence, or just the paradox that holds us back.