An example of the use of ethos is when Bogard writes, “Already the World Health Organization classifies working the night shift as a probable human carcinogen, and the American Medical Association has voiced its unanimous support for light pollution reduction efforts and glare reduction efforts at both the national and state levels”, which shows that his argument is valid due to the fact that the American Medical Association agrees that light pollution should be reduced. It strengthens his argument because the readers now see that Bogard is not alone in his cause. The American Medical Association is a major group that has a large amount of validity. It also builds on credibility because the World Health Organization says that working at night is a probable carcinogen which moves people to see that natural darkness is of much importance. The readers can not deny that light pollution needs to be reduced if major medical groups say it is causing harm to the human population which persuades the readers that Bogard’s argument is important and that they should take action to decrease light pollution. In conclusion, Paul Bogard uses many types of persuasive tools including logos and relative data, pathos, and ethos in his article “Let There Be Dark”. All of the tools he uses contribute to strengthen his argument that natural darkness should be preserved and light pollution should be heavily