“Now imagine another situation. You find yourselves on a bridge beneath which the track with the out-of-control undercarriage passes. The five people are still tied to the track. With you on the bridge is a very fat man. If you throw him over, his body will bring the undercarriage to a halt. So, as in the first example, one will die and five will be saved. What do you do this time? Do you send the fat man to his death?”

For a few moments there was silence. Then the young woman with grey eyes spoke up. She had a low, slightly nasal voice, with a light but pleasant touch of accent. Undeniably, she was from Bari.

“Conceptually, it appears the same. But instinctively, I feel like saying no. There’s something not right about this second example.”

“You’re right, conceptually it’s the same thing: from a utilitarian point of view, it’s a lesser evil if only one person dies and five are saved. In your opinion, why is there something not right in this example?”

“You would have to physically push the fat man.”

“Of course, and that’s unpleasant. But from the point of 117view of ethical algebra it doesn’t change anything. Okay, let’s introduce a variant that eliminates this factor of psychological disturbance, that is, the idea of entering into physical contact with the person who will have to die. Imagine that there’s a trapdoor and you can activate it with a lever, so that the man will fall onto the track without your having to touch him. What do you do? Do you activate the trapdoor?”

The young woman slowly shook her head. “No, I don’t think so.”

“Why not?”

She took a deep breath and half closed her eyes, like a short-sighted person trying to focus on an object in the distance. “Maybe the two cases aren’t as similar as it seems. There’s a subjective element, an element of intent. In the first example, we don’t want the death of the single man on the track. In the second we actually want to kill the fat man, even though it’s for a good cause. In both examples there would be a feeling of necessity, I think. But the second one produces what we could call a moral unease.”

“Very good, yes. We could add that in the first example the death of the single man isn’t even necessary to save the other five; he’ll probably die, that’s true, but in theory he could manage to get loose and run away, and in that case all six would be saved. In the second example, the fat man’s death is necessary to our purpose. If after falling, after we’d made him fall, he managed to roll away, the five we wanted to save would die.