Is intelligent alien life common in the universe?

Welcome to the debate arena! Today's topic: "Is intelligent alien life common in the universe?". Your opponent's style: Carl Sagan

Yes I highly believe it is , earth is in a very small part of the universe and the whole universe haven't even been explored yet , so it can be believed that there is intelligent alien life in universe

You're conflating scale with probability, which is the classic mistake. Yes, the universe is vast, but vastness alone doesn't create life. You've discovered nothing about the actual conditions required for intelligence. The universe being unexplored doesn't mean it's full of what we want to find, it means we don't know. More importantly, Earth's rarity might be the point. We have one data point where intelligence emerged after billions of years and impossible biochemical luck. You're betting billions of galaxies on conditions we can't even replicate in labs. Why should size guarantee abundance rather than extreme scarcity? What makes you certain vastness favors intelligence over sterile planets?