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BIOUNCERTAINTY - ERC Starting Grant no. 805498

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Ignorance of Law: A Study in Experimental Jurisprudence

Research project "Ignorance of Law: A Study in Experimental Jurisprudence" funded by the National Science Centre, Poland under the OPUS 24 programme. Principal investigator: Dr. Piotr Bystranowski

Basic information

  • Project title: Ignorance of Law: A Study in Experimental Jurisprudence
  • Duration: 8th December, 2023 – 7th December 2027
  • Principal investigator: Dr. Piotr Bystranowski (

Popular description

Should one’s responsibility for violating a norm be mitigated by one’s ignorance of the norm’s existence? Most of us could easily imagine situations in which saying “I didn’t know I wasn’t allowed to do it” is a sensible, perhaps convincing, excuse. On the other hand, however, most of us believe in the binding force of the ancient adage that ignorance of law doesn’t excuse and, therefore, nobody should escape responsibility by claiming ignorance of legal norms.

This apparent inconsistency in our intuitions is mirrored in philosophical discussions on the ignorantia iuris principle. For centuries, philosophers have been aware that applying the principle rigorously can lead to instances of injustice in specific cases of punishing people who were not aware of the unlawful character of their deeds. Many scholars claimed that such injustices are a price worth paying for some greater good, while others could not accept them and postulated a radical reinterpretation of the traditional doctrine.

These philosophical debates are as heated as ever in our times, that is, in the times of the unlimited growth in law’s technicality and complexity, when not even specialists can keep track of relevant regulations and when law comes nowhere near to the ideal of correspondence with intuitive, universally shared moral convictions.

This project is the first one to systematically analyse the topic of the ignorantia iuris principle from the perspective of experimental philosophy. We assume that conflicting views on the principle result from diverging intuitions that provide starting point for debating scholars. Hence, we will analyse folk intuitions regarding the responsibility of legally ignorant individuals. The main objective of this project is to assess the reliability and robustness of such intuition, which will help to untangle philosophical conundra in this area.

We will conduct a series of experimental studies on lay people’s intuitions, building on the existing literature in experimental philosophy of law (experimental jurisprudence) and using up-to-date

methods from cognitive psychology and other social and cognitive sciences. Furthermore, in many such studies we will compare intuitions of lay people and legal experts as well as (making use of the wide network of international collaborators in this project) intuitions of people coming from different jurisdictions and legal cultures.

We expect this project not only to be of a fundamental importance to legal philosophers (who will be provided with data that can be used to critically reevaluate their arguments) but it can also deliver relevant empirical data to policymakers and legal reformers.