Omission effect

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The so-called omission effect , even omission error called ( English omission bias ) is the name given to a procedure described by the behavioral sciences phenomenon, according to which an action subjectively is considered risky as another option behavior, which consists in a failure. From a normative point of view, actions are often more heavily sanctioned than omissions, even if the consequences of both behavior options are the same.


When faced with the choice of undertaking an action possibly associated with negative consequences or omitting it, which then leads not possibly but certainly to negative consequences, people tend to omit. This tendency results from the fact that the responsibility for a negative result that one has brought about is perceived as more difficult than the responsibility for a negative result that one did not bring about or has simply not prevented by failure. The ethical evaluation of an act through omission on the one hand and an act through active doing on the other hand is significantly different; the degree of responsibility or guilt is generally rated higher in active action than in action through omission.

Jonathan Baron explains the term in Thinking and Deciding with an example :

Athlete A knows that he will have to compete with the superior opponent B the next day. He also knows that B has a certain food allergy.
Variant 1: At dinner together, A ensures that B consumes the allergen in order to be weakened the next day. (Active action)
Variant 2: B, ignorant of the situation, wants to eat food that contains the allergen. A notices this in good time, but does nothing about it. (Acting through omission)

The behavior according to variant 1 is generally assessed - by third parties as well as by A himself - as more reprehensible than acting according to variant 2.

Another example illustrates the problem of the omission effect:

A doctor has to look after a group of patients with the same illness. The disease is always fatal if left untreated. The only drug available has severe side effects that will kill a fifth of patients. The doctor will therefore tend not to administer the drug or to administer it with a delay, because he will feel responsible for any death that occurs as a result of the administration, whereas if the disease is untreated he will be not (or less) responsible for the death that occurs feels, although then all patients will die.


The different evaluation of action and omission is reflected in the fact that in criminal law only action is generally punishable, while omission is only punishable if this is expressly mentioned in the criminal law norm, such as failure to provide assistance . The ethical imbalance is reduced by the construct of the guarantor . According to this, omission is to be ascribed to a person like active action if this person has a special duty of care to the injured party. Such a due diligence relationship can be established in a natural way - such as with parents towards their children - or contractual, such as between the homeowner and tenant. This is explained in the following example:

The parents of a toddler celebrate a garden party with friend X. The parents have a guarantor position for the child, but X is not. The toddler climbs into the pool and drowns. The parents and X do not act, but watch what happens. In the case of the parents, this will lead to criminal liability for an intentional homicidal offense (§ 211, 212 StGB (D) - murder, manslaughter), while in the case of X only a criminal liability for failure to provide assistance according to § 323c StGB (D) is possible.

The ethically different valuation between active action and omission with regard to the omission effect is criticized from a consequential ethical point of view. The poet speaks:

"All the nonsense that happens is not only to blame for those who do it, but also for those who do not prevent it."

- Erich Kastner

While advocates of consequentialism consider the omission effect to be a cognitive deception, there are other moral-philosophical approaches that try to justify the different evaluation. In practical philosophy, representatives of the ethics of responsibility argue that there are rational reasons for evaluating actions more than omissions, since this is the only way to meaningfully limit personal responsibility and to prevent excessive demands.

In addition to the omission effect, there is also the action bias , according to which there is a tendency in other situations to prefer active options for action. So tend z. For example, goalkeepers in football encourage them to jump after the ball, even if this does not reduce their chance of scoring.


Rolf Dobelli wrote in his bestseller 'The Art of Clear Thinking':

“Is it [the Action Bias] the opposite of the Omission Bias? Not quite. Action bias comes into play when a situation is unclear, contradictory, opaque. Then we tend to be busy, even if there is no good reason for it. In the case of Omission Bias, the situation is usually clear: future damage could be averted by acting today, but averting damage does not motivate us as strongly as reason would.

Omission bias is very difficult to recognize - renouncing action is less visible than action. The 68 movement, you have to admit it, saw through it and fought it with a concise slogan: "If you are not part of the solution, you are part of the problem."

See also

Commission bias

Individual evidence

  1. Franz Eisenführ, Martin Weber: Rational decision-making. 4th, revised edition. Springer, Berlin et al. 2002, ISBN 3-540-44023-2 , p. 369.
  2. For this paragraph as well as the examples in this article: Mark Daniel Schweitzer: Cognitive illusions in court. An empirical study. Dissertation Zurich 2005, Chapter 12, No. 1 ff., Available online .
  3. In many legal systems; here using the example of German criminal law.
  4. ^ Robert Spaemann : Basic moral concepts. (Good / bad, pleasure principle / reality principle, self-interest / sense of value, I / the others, conscience / serenity, purpose / means) (= Beck series. Vol. 256). 8th edition. Beck, Munich 2009, ISBN 978-3-406-59460-1 , p. 70.
  5. ^ Rolf Dobelli: The art of clear thinking