Physiological features categorize people into races
Outward appearance and ancestry - which are biological and unchangeable - define a person's race.
(1 of 2) Next argument >
Societies have racially categorized people by physiological features since antiquity. Today, in countries like Brazil, the US, the UK, people often identify one another's race based on skin color. Identification based on skin color is easy for US Americans to do because of the migration and colonization history of North America. The idea that outward physical appearance determines one's race is also prevalent in South Africa and the UK. The idea that physiological features, such as skin color, determine race is woven into societies and taught to children at an early age.  One study has shown that children as young as 3 months old in the US begin to racially categorize people. 
[P1] Races are defined by outward appearance or other physiological features.
Rejecting the premises
People may categorize someone as a certain race by outward appearance, but that person may not identify with that race (e.g. golfer Tiger Woods)