deletions | additions       diff --git a/Lecture_17_Trade_and_or__.md b/Lecture_17_Trade_and_or__.md  index bb03869..0ff00f2 100644  --- a/Lecture_17_Trade_and_or__.md  +++ b/Lecture_17_Trade_and_or__.md 
...
* * individualism versus culture  Mutual benefit motivates trade  * *  selfish * *  trading parties well-informed about their own utility Altruism motivates, to some extent, aid  * *  warm glow from giving * *  donor not necessarily well-informed about recipient utility