I have no doubt my dogs think. They have a short-term version of planning and will work together to accomplish a goal. Like opening a gate — or dismembering a toy. Surely they would hunt together if they had something to hunt. Dogs are, after all, pack animals.
They communicate. We watch them. They sit silently staring into each other’s eyes. Then they get up, together, and go out to bark, or to the kitchen to remind us they need to eat, now please. I suspect they believe we won’t remember to feed them unless they remind us.
What forms do their thoughts take? They don’t use words. Even though they understand some words if we use them, I doubt that’s how they form ideas. So they must employ their other senses. How much is visual? Do they also think in sound and scent? It’s obvious they know what they want. They can be remarkably clever and creative in getting it … but how can they plan with no words?
Now and again, I try to “think” without words. I always fail. Inevitably, anything in my head comes with narration, conversation, and a lot of subtext.
Dolphins and whales talk to each other in some version of language, but words used human-style is apparently species-specific. We can teach other creatures to understand and sometimes even use words, but it’s unnatural for them. Only people need words. It’s not only how we communicate, it’s inherent to our understanding of our world. It’s the way we categorize everything, remember anything.
Ideas and concepts can’t exist without words. Language has the hooks on which we hang everything, real and conceptual. We are the only species that needs a spoken language and the only one that writes. Along with the opposable thumb, it’s how we rule the earth.
If we were to lose our languages, we would probably lose it all. I don’t think thumbs would save us.