Note that there is a subtler mechanism than brute suppression that puts strict limits on our effective thoughtspace: the culture systematically distracts us from thinking about the deep, important questions by loudly and constantly debating superficial ones. Here are some examples:

• Should the US go to war in Iraq? vs. Should the US have an army?
• Should we pay teachers more? vs. Should public education exist?
• Should healthcare guaranteed by the federal government? vs Should the federal government be disbanded?
• Should we bail out the banks? vs. Should we ban long term banking?
• Should we allow same-sex marriage? vs. Should marriage have any legal relevance?

Notice how the sequence of psychological subterfuge works. First, the culture throws in front of you a gaudy, morally charged question. Then various pundits present their views, using all the manipulative tactics they have developed in a career of professional opinion-swaying. You look around yourself and find all the other primates engaged in a heated debate about the question. Being a social animal, you are inclined to imitate them: you are likely to develop your own position, argue about it publicly, take various stands, etc. Since we reason to argue, you will spend a lot of time thinking about this question. Now you are committed, firstly to your stand on the explicit question, but also to your implicit position that the question itself is well-formulated.