This article presents a bilingual edition of Edmund L. Gettier's "Is Justified True Belief Knowledge?" (1963), where he presents counterexamples to the definition of "knowledge" as "justified true belief." Gettier argues that the conditions stated in this definition do not constitute a sufficient condition for someone to know a given proposition. He provides two cases to illustrate this point: 1. **Case I**: Smith has strong evidence for the conjunction "Jones will get the job and Jones has ten coins in his pocket." He infers that "Jones will get the job has ten coins in his pocket" is true, and he is justified in believing it. However, Smith does not know that this is true because he is basing his belief on the number of coins in Jones's pocket, which is actually in Smith's pocket. 2. **Case II**: Smith has strong evidence for "Jones owns a Ford." He infers and accepts "Either Jones owns a Ford or Brown is in Boston" as true, and he is justified in believing it. However, Smith does not know that this is true because Jones does not own a Ford and Brown is actually in Boston, which is the place mentioned in the inference. Gettier concludes that these examples show that the definition of "justified true belief" does not provide a sufficient condition for knowledge.This article presents a bilingual edition of Edmund L. Gettier's "Is Justified True Belief Knowledge?" (1963), where he presents counterexamples to the definition of "knowledge" as "justified true belief." Gettier argues that the conditions stated in this definition do not constitute a sufficient condition for someone to know a given proposition. He provides two cases to illustrate this point: 1. **Case I**: Smith has strong evidence for the conjunction "Jones will get the job and Jones has ten coins in his pocket." He infers that "Jones will get the job has ten coins in his pocket" is true, and he is justified in believing it. However, Smith does not know that this is true because he is basing his belief on the number of coins in Jones's pocket, which is actually in Smith's pocket. 2. **Case II**: Smith has strong evidence for "Jones owns a Ford." He infers and accepts "Either Jones owns a Ford or Brown is in Boston" as true, and he is justified in believing it. However, Smith does not know that this is true because Jones does not own a Ford and Brown is actually in Boston, which is the place mentioned in the inference. Gettier concludes that these examples show that the definition of "justified true belief" does not provide a sufficient condition for knowledge.