Memory is not a unitary phenomenon. Even among the group of long-term individual memory representations (known in the literature as declarative memory) there seems to be a distinction between two kinds of memory: memory of personally experienced events (episodic memory) and memory of facts or knowledge about the world (semantic memory). Although this distinction seems very intuitive, it is not so clear in which characteristic or set of interrelated characteristics lies the difference. In this article, I present the different criteria proposed in the philosophical and scientific literature in order to account for this distinction: (1) the vehicle of representation; (2) the grammar of the verb “to remember”; (3) the cause of the memory; (4) the memory content; and (5) the phenomenology of memory representations. Whereas some criteria seem more plausible than others, I show that all of them are problematic and none of them really fulfill their aim. I then briefly outline a different criterion, the affective criterion, which seems a promising line of research to try to understand the grounds of this distinction.Memory is not a unitary phenomenon. Even among the group of long-term individual memory representations (known in the literature as declarative memory) there seems to be a distinction between two kinds of memory: memory of personally experienced events (episodic memory) and memory of facts or knowledge about the world (semantic memory). Although this distinction seems very intuitive, it is not so clear in which characteristic or set of interrelated characteristics lies the difference. In this article, I present the different criteria proposed in the philosophical and scientific literature in order to account for this distinction: (1) the vehicle of representation; (2) the grammar of the verb “to remember”; (3) the cause of the memory; (4) the memory content; and (5) the phenomenology of memory representations. Whereas some criteria seem more plausible than others, I show that all of them are problematic and none of them really fulfill their aim. I then briefly outline a different criterion, the affective criterion, which seems a promising line of research to try to understand the grounds of this distinction.Memory is not a unitary phenomenon. Even among the group of long-term individual memory representations (known in the literature as declarative memory) there seems to be a distinction between two kinds of memory: memory of personally experienced events (episodic memory) and memory of facts or knowledge about the world (semantic memory). Although this distinction seems very intuitive, it is not so clear in which characteristic or set of interrelated characteristics lies the difference. In this article, I present the different criteria proposed in the philosophical and scientific literature in order to account for this distinction: (1) the vehicle of representation; (2) the grammar of the verb “to remember”; (3) the cause of the memory; (4) the memory content; and (5) the phenomenology of memory representations. Whereas some criteria seem more plausible than others, I show that all of them are problematic and none of them really fulfill their aim. I then briefly outline a different criterion, the affective criterion, which seems a promising line of research to try to understand the grounds of this distinction.Memory is not a unitary phenomenon. Even among the group of long-term individual memory representations (known in the literature as declarative memory) there seems to be a distinction between two kinds of memory: memory of personally experienced events (episodic memory) and memory of facts or knowledge about the world (semantic memory). Although this distinction seems very intuitive, it is not so clear in which characteristic or set of interrelated characteristics lies the difference. In this article, I present the different criteria proposed in the philosophical and scientific literature in order to account for this distinction: (1) the vehicle of representation; (2) the grammar of the verb “to remember”; (3) the cause of the memory; (4) the memory content; and (5) the phenomenology of memory representations. Whereas some criteria seem more plausible than others, I show that all of them are problematic and none of them really fulfill their aim. I then briefly outline a different criterion, the affective criterion, which seems a promising line of research to try to understand the grounds of this distinction.Memory is not a unitary phenomenon. Even among the group of long-term individual memory representations (known in the literature as declarative memory) there seems to be a distinction between two kinds of memory: memory of personally experienced events (episodic memory) and memory of facts or knowledge about the world (semantic memory). Although this distinction seems very intuitive, it is not so clear in which characteristic or set of interrelated characteristics lies the difference. In this article, I present the different criteria proposed in the philosophical and scientific literature in order to account for this distinction: (1) the vehicle of representation; (2) the grammar of the verb “to remember”; (3) the cause of the memory; (4) the memory content; and (5) the phenomenology of memory representations. Whereas some criteria seem more plausible than others, I show that all of them are problematic and none of them really fulfill their aim. I then briefly outline a different criterion, the affective criterion, which seems a promising line of research to try to understand the grounds of this distinction.A memória não é um fenômeno unitário. Mesmo entre o grupo de representações de memória individuais de longo prazo (conhecidas na literatura como memória declarativa), parece haver uma distinção entre dois tipos de memória: memória de eventos experimentados pessoalmente (memória episódica) e memória de fatos ou conhecimentos sobre o mundo (memória semântica). Embora essa distinção pareça muito intuitiva, não é tão claro em qual característica ou conjunto de características inter-relacionadas reside a diferença. Neste artigo, apresento os diferentes critérios propostos na literatura filosófica e científica para dar conta dessa distinção: (1) o veículo de representação; (2) a gramática do verbo “lembrar”; (3) a causa da memória; (4) o conteúdo da memória; e (5) a fenomenologia das representações da memória. Embora alguns critérios pareçam mais plausíveis que outros, mostro que todos são problemáticos e nenhum deles realmente cumpre seu objetivo. Em seguida, descrevo brevemente um critério diferente, o critério afetivo, que parece uma linha de pesquisa promissora para tentar entender os fundamentos dessa distinção.