The trolley problem is an ethical hypothetical meant to propose a seemingly insolvable moral dilemma. A trolley is traveling along a track toward a location where four persons are tied to the tracks. These four will die if the trolley continues on its path. However, you are standing next to a lever, which can divert the trolley to another track, where only one person is tied to the track. Should you pull the lever, killing one but saving four? Or should you refrain from acting, and allow the four to die?
The three fonts of morality are (1) intention, (2) moral object, (3) circumstances.
For the act of pulling the lever:
The intention is to save four lives. The death of the one innocent is not intended. So the first font is good.
The circumstances are that, if you pull the lever, four lives are saved and only one is lost. So the reasonably anticipated good consequences morally outweigh the bad, making the third font good.
But three good fonts are needed for any act to be moral. The font of the moral object is what will determine the morality of this act, since the other two fonts are good.
This act has two moral objects. The concrete act of pulling the lever switches the trolley from one track to another. This switch is inherently ordered to save four lives, which is a good moral object. But it is also inherently ordered toward killing one innocent, which is an evil moral object. When an act has more than one object, any evil in the object makes the act intrinsically evil, despite other good moral objects.
Since the act of pulling the lever is intrinsically evil, it cannot be done, not even to save a thousand lives.
The act of omission, that is to say, the decision to refrain from pulling the lever, has the good intention to avoid killing an innocent, and has the good moral object of refraining from an intrinsically evil act. The consequences of this act of omission would seem to be bad, since four lives are lost and only one is saved. But consequences include more than a simple accounting of lives lost. The moral weight of lost lives depends on how proximate or remote the deaths are to the chosen act.
If you do not pull the lever, four lives are lost, and only one is saved. But the saved life is proximate to the decision not to act, whereas the four lost lives are remote from the same decision. You did not place those persons on the track, nor direct the trolley toward them. The situation which endangers their lives is not of your making, so the consequences of their deaths is reduced in moral weight, by being remove from your act. Furthermore, you cannot save them without committing an intrinsically evil act, that is to say, without sinning gravely, and this reduces the moral weight of their deaths further. So the font of consequences is actually good.
The act of pulling the lever is intrinsically evil. The act of omission, i.e. the decision not to pull the lever, has three good fonts. Therefore, you must not pull the lever.
Saint Catherine of Siena stated the moral principle needed to understand this moral dilemma:
“The light of discretion (which proceeds from love, as I have told you) gives to the neighbor a conditioned love, one that, being ordered aright, does not cause the injury of sin to self in order to be useful to others, for, if one single sin were committed to save the whole world from Hell, or to obtain one great virtue, the motive would not be a rightly ordered or discreet love, but rather indiscreet, for it is not lawful to perform even one act of great virtue and profit to others, by means of the guilt of sin.” [The dialogue]
It is not moral to commit one sin, especially a sin which is intrinsically evil and gravely immoral, in order to obtain a good consequence, not even “to save the whole world from Hell”.
Pope Saint John Paul II: “In the case of the positive moral precepts, prudence always has the task of verifying that they apply in a specific situation, for example, in view of other duties which may be more important or urgent. But the negative moral precepts, those prohibiting certain concrete actions or kinds of behavior as intrinsically evil, do not allow for any legitimate exception.” [Veritatis Splendor 67].
It is not moral to kill an innocent, not even to save a thousand lives. For example, killing an embryo to obtain stem cells, which can be grown in a lab so as to provide medicine to save many lives is still intrinsically evil, even though a thousand lives would be saved.
Another example: if you are told by terrorists to kill one innocent person, or else they will kill one thousand innocents, you cannot comply. Killing the one innocent is intrinsically evil. Allowing many to die when you are not able to act without sin is not intrinsically evil. The moral law requires us to avoid all grave sins, especially those that are inherently immoral, such that no purpose, however noble, and no circumstance, however dire, can justify the act.
If the answer to the trolley problem were to pull the lever, and so kill one innocent to save four, then this would imply that we must do whatever any terrorist tells us to do, to save a thousand lives, even if they demand that we kill a hundred innocents. It would imply that the government could take innocent life, whenever it would save other persons’ lives. For example, if killing one innocent would provide organs to save four lives, then the government could take that person’s life to save the four — IF the answer to the trolley problem were to pull the lever.
Consequences and intention do not enter into the decision, since pulling the lever is intrinsically evil and refraining from pulling it is not. We are never required by the moral law to act when the act is a sin. In fact, we are able and are required to avoid all grave sin.
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