Why should a 21st century student study the views of 19th century scholars?

The only way to learn about the future is to study the past. The various 19th Century scholarly minds (and the 18th, and 17th, and 16th, and so on...) nearly always had some good ideas to ponder, and you can learn a lot about life and stuff in general from them. Now, they also had some dumb stuff on their minds too, so I wouldn't say that you should just absorb and gulp down alltheir stuff, but you should be able to separate the wheat from the chaff, so to speak. The 19th century gave us philosophers and scientists from Freud to Dewey (the educator, not the Admiral) and even the early part of the century hosted contributions from men like Thomas Jefferson.