Proposals for extending the United States school year to bring it more in line with its European and Japanese counterparts are often met with the objection that curtailing the schools’ three-month summer vacation would violate an established United States tradition dating from the nineteenth century.
Opposing Point
People object to extending the school year because the three-month summer vacation is a U.S. tradition dating from the nineteenth century.
Author's Setup
True, schools closed for three months in the nineteenth century, but only because rural harvests depended on children's labor.
Conclusion
If any policy could be justified by appeals to tradition, it would be the policy of determining the school year length according to the needs of the economy (since that is what the original tradition actually reflects).
Evaluate
The author is identifying the real tradition by looking at the original reasons. The "three-month summer break" looks like the tradition, but the author argues the actual tradition is the underlying principle: matching the school year to economic needs. The bridge: traditions are properly identified by their original purposes, not by their surface form.
Goal
Find the principle that lets us read traditions through their original reasons rather than their surface practices.