I am using the definition from the times of Descartes. Perhaps I missed the moment when the word "thinking" began to refer to arbitrary cognitive processes.

I will try one more time.

The rules of logic require precise definitions (as best as we currently able to produce) and to follow the rule of substituting equal for equal only. The socially constructed memes cannot be substituted for definitions, no matter what hipsters would write in blog posts.

Thinking, as in "I think" or "I am" or how Descartes put it "I think therefore I am", is based on a language. Language is required for thinking and abstract thinking and reasoning. Language comes before the notion of "I". Before any abstractions.

Argumentation is quite straightforward. Human languages has been evolved together with related brain centers and this process took alot of time. There is a fundamental gap between association of sounds or cries with some sensory patterns and ability to say "I am". How long it took? Some primates are capable of learning very rudimentary sign language after years of rigorous training, but they are incapable of developing of (or even grasping) the notion of "I" on their own. Now you might see the gap.

I would argue that language comes prior to abstract reasoning and abstract thinking, and that they have been evolved together in a mutually recursive relationship. Think of the mutual recursion of #'eval and #"apply as the best example of mutual recursion I know.

Thinking, I would say, started with a primitive, rudimentary language and then related brain circuitry has been selected by evolution. Social evolution and biological evolution together.

One could see the very process of emergence of self-awareness and self-consciousness in babies as a gradual process parallel (or rather based on) language acquisition. The fundamental difference is, of course, that all necessary brain centers are already developed and encoded in DNA (but they are still has to be trained).

This line of arguments is for justifying and supporting the postulates of Descartes about fundamental difference between a human and an animal (creationist nonsense aside). To put it another way - there is not a single scientifically proven contradictions with his definitions.

I would spare you from a lecture on basic linguistics - there are much better figures in the field. The only reference I would like to make is to the postulate of Chomsky, that language acquisition is a process, similar to growing of an organ. So, the story about Evolution is applicable to a capacity as it is applicable to any organ or a subsystem.

So, thinking in its classic definition is the capacity based on a language. It is implemented in corresponding brain centers and related circuitry and is impossible as ability without underlying lower level machinery which takes long and unique path to evolve.

As far as we know, no species went to the same evolutionary pathway which humans did to evolve even a rudimentary natural language in linguistic sense (uniform, rule-governed, arbitrary composition).

So, animals cannot think the way humans do.

BTW, in this chain of reasoning I have demonstrated the kind of thinking no animal is capable of and, hopefully, why it is so.