How Many Choices Do We Make? How Many Are Difficult?

I have been asked to write about some of the choices I have had to make as a scientist — choices relating to social responsibility. This is a very dangerous task, since it may easily become a tale of a battle between evil and good, with oneself as the hero. In fact, I do not know how to avoid that trap: there have been battles with very much to lose, and one had to mobilize a strong belief in the cause one was fighting for.