An excuse is a claim that takes what appears at first glance to be a state that a person with good desires would have avoided creating, and blocks the inference that the agent who created it deserves condemnation or punishment.
There are six types of excuses - accident, false belief, denying harm, consent, greater good, and deserved punishment.
“Accident” is a type of excuse where an agent claims, in effect, that a person with good desires could not have done something other than what the agent did in a given circumstance.
For example, a car goes through a stop sign runs over a pedestrian. At first glance, this appears to be a case in which the driver did something that a person with good desires would not have done. The person with good desires would have an aversion to a state in which the pedestrian is laying on the ground injured. This aversion would have motivated the agent to take steps to prevent that from happening by stopping and then continuing through the intersection after determining the way is clear. This agent did not stop, and obviously did not make sure that the intersection was clear before going through it. Therefore, he did not act as a person with good desires would have acted. At least, this is how it appears at first glance.
However, the driver responds to our accusation with the claim of “accident”. He claims that the brakes failed and that, even though he tried to stop, he was not able to.
A claim of “accident” is a claim that a person with good desires could not have prevented the creation of the adverse state. His aversion to creating such a state would have been impotent in the actual circumstances.
Let us assume that an examination of the brakes shows that they did, in fact, fail. The driver applied the brakes in a timely fashion. Nothing happened. No other option was available in the time permitting to avoid hitting the pedestrian. In this case, the claim of “accident” is substantiated. In fact if we assume that the brakes had been tampered with, desirism leads us to conclude that the driver of the car is not guilty of creating a state in which a pedestrian was injured. The person who tampered with the brakes is guilty of creating that state. This state would not have existed if the desires of the person tampering with the brakes would have been good desires.
In this case, let us assume that the brakes had not been tampered with. They had simply failed.
Desirism tells us that the question of culpability (of blameworthiness) has not yet been answered. We have another question to answer. Would a person with good desires have prevented the brakes from getting into a state in which they failed.
We can see here, as well, that a discovery that the brakes had been tampered with would exonerate the driver (unless the driver is the person who tampered with the brakes).
We also recognize a moral distinction between the following two scenarios:
Scenario 1: The driver had bought the car about 10 years ago and never had the brakes inspected or maintained.
Scenario 2: The driver was on his way home after having the brakes inspected – an inspection where the mechanic working on the brakes made a mistake that caused the braking mechanism to fail.
In the first scenario, we can still conclude that the driver lacked the interest that people generally have reason to promote of preventing the state in which the pedestrian got ran over. The driver who is averse to creating such a state would demonstrate their concern by acting in ways that would prevent such a state. Failure to get the brakes inspected on a regular basis implies a lack of concern with avoiding the states that failed brakes could create – a lack of interest in the welfare of others that others generally have many and strong reasons to promote. This driver can still be condemned.
In the second scenario, the “accident” excuse would be valid. The driver demonstrated a proper concern for preventing the state in which the pedestrian was hurt, and got caught in a situation where even a person with good desires could not have prevented the creation of such a state. Unless, of course, there is evidence to show that mechanic was “unreliable but cheap” and the driver had selected him for that purpose. This, too, indicates that the driver was more concerned with saving money than with preventing a situation in which a pedestrian has been struck and injured – which is not the desire set that people generally have reason to promote.
All of these features of the “accident” excuse are implied by the assumption that we are looking for the desires involved in creating such a state, looking to determine if anybody acted on desires other than those that people generally have reason to promote or inhibit. We are looking for whether the driver was concerned enough to avoid such a situation to go through the intersection carefully and to have his brakes inspected by a qualified inspector. We are looking at whether somebody else tampered with the brakes or a careless mechanic had damaged the brake system.
All of this represents an attempt to trace an accident back to some desire that people generally have reason to inhibit (or aversion that people generally have reason to promote) through condemnation and punishment. Please note that the effect is meant to apply not only to the person who is condemned or punished, but to serve as a lesson whereby others in society also adopt those attitudes that may serve to prevent similar events in the future.
If it is the case that the unfortunate event truly resulted from circumstances such that people with good desires could not have prevented the result, then it may be tragic, but there is no justification for condemnation.
It was an accident. Those things happen. It's nobody's fault.