system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are we able to hold and engage in conversations, seemingly without thinking?

When someone strikes up a conversation we are able to respond quite fast. There's usually not much of a pause when it's the other person's turn to speak. Is this just reaction? Every conversation is a bit different, yet no deep thought ever seems to cross our mind when engaged in conversation.
gpt
You _are_ thinking, deeply and intensely, when engaging in conversation. But this thinking is something your brain is innately wired to do.  It's as natural a human behavior as walking, or looking out on the world and recognizing what you are seeing, or using a tool. All these are really intense and difficult problems that we tackle automatically and easily, because we are adapted for doing just these things. 

Contrast this with doing algebra or playing chess.  These are things we have no innate ability  to do, so we have to do it the "long way" by applying our general-purpose conscious intelligence to the problem. Holding a pencil and writing out 124 + 139 = 263 is a _vastly_ more difficult problem than solving the equation, but most people could accomplish the writing without "thinking", while the math problem takes some thought, since the motor-control and visual recognition are things the brain is primed to do, unlike addition.

This threw a lot of early AI researchers, who originally expected things like machine vision to be easily solved on the way to conquering big problems like chess and advanced math.  They learned it was much easier to make a computer beat the world champion in chess than to make one engage in a sensible conversation.  Which gives you an idea how difficult it is.