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Google rode into China four years ago on a wave of optimism about the Internet's power to spread information within closed societies. At that time I was living in Hong Kong, where I had been writing about China and the Internet for this newspaper. I described online petitions, vibrant Web communities, and netizens' successful attempts to unearth news that authorities tried to block.

I believed that companies like Google would broaden the market for information. So when Google launched its Chinese site, Google.cn, I was uneasy about the company's decision to censor its search results to comply with Chinese law.

But Google eventually convinced me, along with other skeptics, that it had made the right calculation. "Our continued engagement with China is the best (perhaps...