Clarification about the usage of "the"

Question

I know that this may be a basic question but I'm severely confused. How do you decide when or not to use "the". For what I've read, if you are referring to objects within a large class (without any specific object in mind), you don't use "the". For example:

• People who workout often tend to be fitter.

But how do you know that you are in such a case? How do I distinguish between a broad class and a not so broad class. It seems sort of idiomatic. It doesn't seem wrong to me if I write:

• The people who workout often tend to be fitter.

Is it just a matter of choice or there is a really a strict rule of usage? If so, how do you distinguish between one case and the other?

Answer 1

In this case, there is a free choice, but there is a slight difference in meaning. But it is nothing to do with the size of the class: it is how you are treating the group of people you are referring to.

The people who workout ...

creates (in my mind, at least) a specific group of people, those who workout. It says nothing about how big, diverse or geographically widespread they are, but it notionally groups them into something. People who workout ... does not do this: it identifies the same people, and makes the same statement about them, but it does not clump them together notionally.

Having said this, I can't find a practical effect of the difference, in this case; but the notional difference is clear in my mind when I think about it.

Answer 2

People who work out... is a general statement about all people who work out.

The people who work out... could be a statement about a more specific subset of people.

For example,

The researchers studied 1,045 individuals over a period of twelve months and found that the people who worked out regularly experienced on average 12 % fewer incidences of conditions X, Y and Z. They therefore conclude that people who work out regularly are significantly less likely to suffer from these conditions.

The first sentence is about the specific subset of people in the study, while the second sentence is a generalised statement about all people.

Alternatively, if the context doesn't describe a subset of 'all people', the use of the could be interpreted as setting yourself apart from the group you describe:

The people who complained about the new colour scheme should get over themselves! There are more important things in life!