What is the meaning of the phrase "to the extent that"?

Solution 1:

There are two related meanings to the phrase to the extent that. The first, relatively concrete, is to set a measurable limit on a statement. Consider

We are of opinion and find that the charge of 12 cents per 100 pounds was unreasonable to the extent that it exceeded 10 cents per 100 pounds....

In other words, the charge was unreasonably excessive, and we know by exactly how much it was, namely by an extra 2 cents per hundredweight. The second usage is limiting as well, but it's more abstract and comparative, equating the scope of one claim to that of another. For instance, from The SAGE Handbook of Organizational Behavior, J Barling and C Cooper editors:

A core premise of this theory in that a goal is motivating to the extent that an individual can visualize its attainment.

This says that some goal will motivate people, but only as much as they can see in their mind's eye what happens when the goal is met. You could dispute this claim by saying that zealots are motivated by devotion and don't need to visualize results at all to stay motivated. But the SAGE theory says otherwise, linking motivation and visualization and saying that the latter limits the former.

You'll notice that what follows that in the phrase to the extent that is a clause. (I've made those italic in the two examples above.) The word that is a subordinating conjuction, i.e., a word that links the independent clause to the subordinate clause.

In the phrase to that extent, that is a determinative modifying extent and pointing out to us which extent is meant. We could modify the first example to say

The charge of 12 cents per 100 pounds exceeded the limit of 10 cents per 100 pounds. To that extent it was unreasonable.

The word that now refers to the 2 cent overcharge that was originally described in the clause it exceeded 10 cents per 100 pounds.

Solution 2:

The meaning depends on the whole sentence.

Basic meaning of

to the extent that

means

to the limits that