Answer: Europeans carried deadly (to the Native Americans) diseases
Explanation: When getting cured of a disease your body will have some type of immunity to the disease. If it is common from where you are then it wouldn't be too harmful. However, Native Americans getting new European diseases harmed them because this was new and they had no immunity. This made these diseases deadly to them.
The Enlightenment thinker was Jean-Jacques Rousseau
Aristotle was the first Greek philosopher to analyze how people can use reason to reach logical, provable conclusions.