Final Answer:
The four key 20th-century trends in African Philosophy are Ethnophilosophy, focusing on traditional thought; Nationalist-Ideological Philosophy aligning with liberation movements; Professional Philosophy applying Western methodologies, and Sage Philosophy exploring wisdom from traditional sages.
Step-by-step explanation:
Ethnophilosophy: Ethnophilosophy emerged as a trend focusing on the analysis and interpretation of traditional African thought systems within specific cultural contexts. Philosophers sought to understand and document indigenous philosophical ideas and values.
Nationalist-Ideological Philosophy: This trend was marked by African philosophers engaging with political and social issues, aligning philosophical discourse with nationalist movements. The emphasis was on using philosophy as a tool for liberation and nation-building.
Professional Philosophy: As Western-style education became more prevalent, African philosophers started engaging in professional academic philosophy. This trend involved the application of Western philosophical methodologies to address universal questions and issues.
Sage Philosophy: Sage Philosophy involved the exploration of the wisdom and knowledge held by traditional African sages or wise individuals. Philosophers sought to extract and analyze the philosophical dimensions embedded in the insights of these traditional figures.