The phrase is a complete sentence: “Practice (实践) is (是) the one and only (唯一) standard (标准) for testing (检验) truth (真理).”
This phrase is arguably one of the most important in the history of the People's Republic of China. Its significance is rooted in the political turmoil of the late 1970s. After the death of Mao Zedong and the end of the Cultural Revolution, China was at a crossroads. Hardliners, known as the “Two Whatevers” faction, insisted on rigidly upholding whatever policies and decisions Mao had made. Deng Xiaoping, seeking to modernize China's economy, needed to break this ideological deadlock. In 1978, an essay titled “Practice is the Sole Criterion for Testing Truth” was published and promoted by Deng's allies. It sparked a nationwide debate and ultimately provided the philosophical justification for his pragmatic reforms. It was a direct challenge to dogmatism, arguing that if a Mao-era policy like collective farming was failing in practice, it should be abandoned, regardless of its ideological origins. This phrase became the ideological cornerstone of “Reform and Opening Up” (改革开放), the period of economic liberalization that transformed China. It gave leaders and ordinary people the permission to experiment, to try new things (like market economics), and to judge them by their results. Comparison to a Western Concept: While similar to the Western proverb “The proof is in the pudding,” the Chinese phrase operates on a much grander scale.
While its origins are political, the phrase is now widely used in various contexts to advocate for a practical, results-oriented approach.