What if we had to choose between

Killing 1 or letting 10 die?

Most people have a point where they say 'kill the one'

The controversy tends to be over precisely where:

Killing 1 or letting 20 die?
Killing 1 or letting 1,0000 die?
Killing 1 or letting all the people in the world die?

Similarly for torturing one to save... However many...