A weakness of Tulving's view is that Cohen and Squire disagreed with Tulvingâs idea that episodic and semantic memory are separate systems. Instead, they argued episodic and semantic memory are part of one type of memory system called âdeclarative memoryâ, because both involve conscious recall. They suggested that semantic memories often develop out of episodic experiences. For example, knowledge about a historical event (semantic) may have first been learned during a specific lesson (episodic). This overlap indicates that the boundaries between episodic and semantic memory are not always distinct, as Tulving claimed. This weakens Tulving's theory as it may oversimplify the structure of memory, reducing its explanatory power.