Cuando uno hace una aserción (sin expresiones de seguro como"creo","me parece","es probable que"...) está afirmando implícitamente que sabe lo que dice. Estar seguro es creer que la evidencia de que se dispone es suficiente, que no está cancelada. Si uno cree que sabe que p, la creencia de que su evidencia es suficiente (que no está cancelada) es una parte constitutiva de su creencia de que p. Si esto es así, entonces no ha habido nunca contraejemplos del tipo Gettier a la definición tripartita del conocimiento (o ha habido muchos menos de lo que se ha supuesto normalmente), porque en los casos tipo Gettier típicos el sujeto tiene una creencia falsa: su evidencia sí que está cancelada. To make a claim is to convey that one knows what one says, i.e., that one is certain. To be certain is to believe that the evidence possessed is enough, that there are not defeaters of one¿s evidence. If one believes that one knows that p, the belief that the evidence is enough (that it is not de- feated) is a constitutive part of the belief that p. If that is true, then there have never been Gettier type counterexamples to the tripartite definition of knowledge (or, at least, there have been much less than it has been thought), because in typical Gettier cases, the belief the subject has is false: their evidence is actually defeated.