The moral circle - who we consider worthy of ethical consideration - has expanded throughout history. Understanding this history helps us think about how animal welfare concerns may continue to evolve.
The expansion of moral consideration to encompass animal welfare has followed the same pattern as other moral progress: dismissed as absurd initially, then debated seriously, then gradually institutionalised. The arc of animal welfare history suggests that current practices we consider normal - factory farming at industrial scale, routine surgical procedures without analgesia, captive cetacean display - may be viewed by future generations with the same horror we view historical practices. This historical perspective argues for taking animal welfare concerns seriously even when they challenge economically entrenched systems.