The characters combine quite literally: 孤立 (gūlì) means “to stand alone” or “to be isolated.” Adding the “-ism” suffix 主义 (zhǔyì) creates “the principle of standing alone”—or, Isolationism.
Historically, China has experienced long periods of what could be described as 孤立主义. The most famous example is the 闭关锁国 (bìguān suǒguó)—“closing the gates and locking the country”—policy of the late Ming and Qing dynasties. This policy severely restricted foreign trade and interaction, born from a desire to maintain internal stability and cultural purity. However, this isolation is now widely seen as a primary cause of China's decline in the 19th century, leaving it vulnerable to foreign powers during the “Century of Humiliation.” This historical trauma deeply shapes the modern Chinese perspective. While American isolationism is often debated as a strategic choice to avoid “foreign entanglements” (a concept dating back to George Washington), Chinese 孤立主义 is almost universally viewed as a recipe for disaster. It is the antithesis of the 改革开放 (gǎigé kāifàng) or “Reform and Opening-Up” policy, which is credited with China's modern economic miracle. Therefore, accusing a policy or country of 孤立主义 in a Chinese context is a strong criticism, implying it is regressive, self-defeating, and ignorant of the lessons of history.
孤立主义 is a formal term primarily used in specific, high-level contexts. You will rarely hear it in casual daily conversation.
The connotation is overwhelmingly negative. It suggests a policy that is doomed to fail in an interconnected, globalized world. There is no positive or neutral spin on this term in mainstream modern Chinese discourse.