The gu, the hu, and the jue are types of bronze libation vessels that were produced in China during the Shang dynasty, almost 4, 000 years ago  Close examination of authentic gu, hu, and jue vessels reveals that they all bear incised patterns symbolizing the taotie, a mythological beast of greed
It must be true then that any bronze libation vessel that does not bear incised patterns symbolizing the taotie is not an authentic vessel produced in China during the Shang dynasty
treating the fact that some members of a category possess a certain characteristic as sufficient evidence that possession of the characteristic is necessary for membership in that category