Content Warning: This section of the guide includes discussions of eugenics and the Holocaust.

Sandel’s argument against bioengineering is rooted primarily in the principle of openness to the unbidden. He attributes this phrase to William F. May, an American ethicist and theologian. By “unbidden,” Sandel and May mean the elements of life that are outside of people’s control. The unbidden is the unexpected, the surprising, or the unpredictable. In an increasingly technologically advanced world, the unbidden is in some senses disappearing. Holding onto and actively valuing that which remains unbidden in the world is an essential ethical principle in Sandel’s eyes. It is also something that many people find very difficult, as it requires a degree of trust in the unknown.

Genetic modification, in Sandel’s view, is inherently antithetical to the principle of openness to the unbidden. It could give parents the ability to choose their children’s genes before they are born, a practice antithetical to the unconditional love and acceptance that Sandel sees as the essence of good parenting. Openness to the unbidden is primarily framed in this text as a parenting principle predicated on humility. Children are inherently unpredictable: Before they come into the world, nobody knows who they will be, how they will look and act, or what they might do with their lives.