For all the differences between the United States and Europe, we share a common challenge: how to improve the social well-being of our citizens without a massive growth in the size and intrusiveness of government. We're convinced that conservatism--properly understood--offers the surest road to social justice. In many conservative circles, "social justice" is synonymous with socialism or radical individualism. No wonder: For decades, the political left has used it as a Trojan horse for its big-state agenda. Yet the wreckage of their policies is obvious. Compared to the U.S., most European economies are struggling with inflation, unemployment, low growth and...