The potato contains vitamin C and amino acids.

[jutfrank]

If we exclude that property, the potato will no longer be the potato, it will become something else. Hence, to contain vitamin C is important.

Okay, but I disagree. It seems to me you're taking something of a scientific approach here. My approach to understanding these things is very different.

Something is a potato if it looks, feels, smells, and tastes like a potato, if you can cook and eat it, if it goes green and bitter if you don't, and if it goes well with fish and mushy peas. My view is that meaning (the relation between language and things) comes from way back in our evolutionary past, when we began defining things in the world around us with respect to how they concern our survival and our negotiation of the environment. It's only in our species' very recent history that we've developed an insight into the molecular world. The scientific way of classifying and defining things is often quite at odds with how we naturally classify and define things.

Moreover, for a property to be kind-denoting or/and essential, it does not have to be sensually perceived or even material. Look at these definitions:
a) The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge.
b) The mind is the set of faculties responsible for mental phenomena.

We can't see, smell or taste an electron or its charge. And the mind is just non-material.

I think the first of these supports my view. The charge of an electron is something that has meaning to a subatomic physicist, but not to an ancient hunter-gather. To a physicist, things like charge, spin, and what have you are just as much definitive properties of particles as shape, size, and colour are to a toddler playing with building bricks. As a scientific definition, a) obviously works well. However, b) is different as it concerns an abstract object. This is a rabbit-hole we might not need to go down. I think that for the purposes of getting to grips with this difficult subject, we ought to stick to tigers and potatoes.

Actually, it is detectable and measurable since it's an acid (material substance). But that doesn't matter (see above).

See above.

I'll respond to the rest of your thoughts later or tomorrow. I'm glad you found that SEP entry on generics. I'll read it too. Let me know if you have anything to ask about what it says.

 

[Alexey86]

The scientific way of classifying and defining things is often quite at odds with how we naturally classify and define things.

That doesn't mean that the scientific way provides less kind-denoting definitions/descriptions than the natural one does, does it?
But I see your point: "grows underground" would be a natural kind-denoting characteristic of the potato.

To a physicist, things like charge, spin, and what have you are just as much definitive properties of particles as shape, size, and colour are to a toddler playing with building bricks.

I'm like a toddler: when I hear "charge", I see "+" or "-" in my mind. Similarly, when I read "contains vitamin C", I see little dots or circles.

As a scientific definition, a) obviously works well.

And again, that doesn't make it less kind-denoting. On the contrary, it's a layman approach that often talks in non-essential subjective terms.

However, b) is different as it concerns an abstract object. This is a rabbit-hole we might not need to go down. I think that for the purposes of getting to grips with this difficult subject, we ought to stick to tigers and potatoes.

OK, let's stick to them. I just want to notice that b) might reveal a weak spot in your approach.

 

[Charlie Bernstein]

. . . Frankly, it raises more questions than it answers.

Don't they all!