Here's a hackneyed phrase I could go the rest of my life without hearing. I finally got around to watching the Battlestar Galactica miniseries from a few years ago, based on several recommendations. The plot revolves around humans who invented cylons, basically robots with advanced AI, to "make their life easier in the 12 colonies". And of course the cylons turn against their creators and try to wipe them all out, which reminds me of the Simpsons episode where Professor Frink says:

Elementary chaos theory tells us that all robots will eventually turn against their masters and run amok in an orgy of blood and kicking and biting with the metal teeth and the hurting and shoving...

It's true, you know. Anyway, in a speech very early on in Battlestar, the commander gives a speech about the history of the cylon wars and says humanity was "playing god." This is a trope of a whole bunch of science fiction. In the I Am Legend movie, the whole thing was caused by an attempt to cure cancer. This tradition goes all the way back to what most consider the first science fiction novel, Frankenstein.

Can somebody please explain what the hell "playing god" means? As far as I can tell, it means "doing science". Why isn't agriculture "playing god"? We're deciding which plants and animals reproduce with which. We're deciding who lives and who dies. Was developing the polio vaccine "playing god"? How about going to the moon?

When we're carrying out science, trying to learn about the world, to uncover some universal truth, to try to improve the lives of people around the world, is that inherently "playing god," or is there some particular line that has to be crossed?