Back in Berkeley in the 90s, Donald Davidson thought you did. His argument was unless we saw a creature use language we would have no evidence for believing it had thoughts. All we would see was a creature in a causal relationship with its environment.
But what if a beaver constructed a ship and stocked it with food, went on a journey, checked the winds and when the winds provided evidence of bad weather adjusted its journey by stopping and getting more food for the longer journey? If the beaver misjudged and overstocked based upon the wind then it mis thought and therefore thought, and this happened without language.