I was just rereading an article I wrote for one of the blogs I write for. Wow, I came up with a really good question.
Basically there's a common pattern people follow of opposing an unwanted something. e.g. during an election they'll vote against the person they don't want. But being in opposition to one thing is not a positive statement of what you do want. One example I gave is that in 2000 and 2004 I voted against George W. Bush but that leaves me with no clue as to whether Kerry would have been a good presidential choice. Voting against Bush is not the same as voting for Kerry.
For that matter opposing gasoline use is not the same as positively saying "I want clean transportation".