It feels like everyone in this conversation is just choosing their own arbitrary definition of computation. The question is, why have you chosen that definition, what makes it useful? As the author points out, if rocks compute, then there is not much meaning to computation as a concept.

Computation in the colloquial sense refers to a sequence of events that happens inside machines that were made by humans in order to calculate some explicit mathematical results that the human operators have some interest in. I think this is a fine definition, and one that includes computers but not humans or rocks. I feel like the author erred in trying to redefine computation into some other abstract concept, muddying the water such that everyone is just talking about what "computation" means to them.

I think the real question we're getting at is, "what is the relationship between what a human brain does to solve a problem, for example moving a body into the correct position to catch a baseball, and what a computer does, which we know is executing explicit math equations to calculate trajectories, inverse kinematics, etc?" Right? We're talking about the illusion of intent, of goals, of the desire to solve problems - and as far as we can tell, rocks obviously do not possess those traits.

"..there is not much meaning to computation as a concept."

I kind of do agree with this.

So, if I want to calculate a parabola, and construct a machine to launch rocks at specific velocities and angles, then this machine is a computer, but if I just throw a rock without wantint to calculate a parabola, no computation has happened?

What if a kid is playing around with my rock launching machine? Is no computation happening because the kid isn't trying to calculate parabolas?

If the machine is just launching rocks at a specified angle and velocity, then no it is not computing a parabola. The rock's trajectory traces a parabola, but it has not been "computed" (in my view). A computation to me involves an explicit mathematical result related to some specific intent or question, not just physical objects playing out the laws of nature. The computer would have to make a statement, a result - "based on my calculations, at time X the rock will be at position Y."

Then you would clearly reject all analog computers, since e.g. an analog adder just involves electrons playing out the laws of nature. A rock launching machine is an analog computer for calculating a parabola. A specific result might be "where is the intersection with some Y value, and you have a platform at the height for that value. The distance the rock lands at would be the X value.

What is the point of reducing everything to nothing, or to the same thing? I mean I get it, technically it's valid, but it's very boring, there's nothing then to talk about. We are humans and we do have subjective experiences and classify things into different groups, and trying to understand the relationships and differences between groups gives us interesting things to think and talk about.

But hey, if a rock and a computer are the same thing, and computation is meaningless, words are meaningless, etc - why have you bothered to say anything at all?

The term "Computer" dates to the 17th century and was used to describe humans performing calculations. "Mechanical Computers" and then "Electrical Computers" were machines that could replace those people. Quite clearly humans can perform computation in the colloquial sense.

"Colloquial" and "historical" are not the same thing. "Colloquial" refers to the meaning implied by a layperson when they use the word in casual conversation today. Maybe you feel that the colloquial usage is less accurate than the historical usage you describe, but most people are talking about machines when they say "compute" or "computer." Math exercises, to my knowledge, never say "compute the value of..." They use other terms. Another example, the "computational theory of mind" would be meaningless and redundant if everyone already viewed the mind as a computer computing things.

"Given X compute the value of Y" was in most of my math textbooks from Algebra on. Some books preferred calculate though.