Terraforming

If this were asked of a planet in a Sci-Fi novel, with it's own non-Terran life and ecosystem, then I think you'd get a better response.

I don't think there would be many people who would disagree that eradicating another lifeform simply to make their planet livable for ours without some extreme circumstance would be wrong, I'm talking mostly about if you feel it would be wrong to change the nature of a planet to suit it to our own needs, after seeing what changes we've made to Earth.

In reply to Venus - I don't think it would be wrong, but it'd be a completely daft thing to do, and the cost involved would be ludicrous.

Well, the population generally continues to grow, and we will eventually run out of living space. Also, in the VERY long term, our sun will collapse into a Red Giant, which will swallow most of the Inner Planets, either completely destroying them or rendering them all barren in a manner somewhat similar to Mercury. This won't happen for billions of years, but if civilization lasts that long, we'll be forced to find a new living locale by then.

In the case of Venus, it'd be for exploration purposes as well as living space and resources to fuel industry. By the time we'd hypothetically be considering terraforming Venus, the cost wouldn't be prohibitive (as that would always be a consideration) and we'd already have means to cheaply ship men and materials from Earth via Space Elevator or something as yet undiscovered.

I'm mainly aiming for the philiosophical side of the argument.