Browse by Decade

Click a decade to see theories that emerged in that era.

• 1920s
  1 theory
• 1930s
  5 theories
• 1940s
  13 theories
• 1950s
  20 theories
• 1960s
  32 theories
• 1970s
  25 theories
• 1980s
  26 theories
• 1990s
  57 theories
• 2000s
  56 theories
• 2010s
  93 theories
• 2020s
  81 theories