In veganism, the question of animal intelligence seems automatically accepted without scrutiny. Vegans have a confirmation bias towards animals and their respective intelligence levels because we’ve taken a profound action by changing how we consume food and products.
Not consuming animal products is one thing, but arming yourself with knowledge against a tide of omnivores who refuse to accept animals as intelligent beings worthy of respect is another.
As a skeptic and an empiricist, I personally yearn to understand the machinations of such an idea. The more I learn, the more the concept of the difference between human and animal cognition dissolves.