The story provides anecdotal evidence. Anecdotal evidence is based on personal observations or experiences and is often used to support arguments or claims. In this case, the story of the person who witnessed the running of the bulls in Spain provides a firsthand account of the event and their perception of mistreatment of the animals. However, it is important to note that anecdotal evidence alone may not be sufficient to make a conclusive argument and should be supported by other forms of evidence such as scientific research or expert opinions.