There's room for reasonable people to disagree over whether or not employers should be required to give advance notice before closing unprofitable factories.

But, since relatively few plant closures result from foreign competition, it's hard to see any justification for including such a requirement in the new trade bill on which Congress is working.Due to union lobbying, however, the provision on plant closures evidently is going to be kept in the trade bill even though that means the entire measure is likely to be vetoed.

What folly!

The proposal to require 60-day notice of not only plant closings but also layoffs involving 150 or more workers is based on the argument that it's only humane to give the employees involved time to look for other jobs.

But how is the economy helped by requiring employers to lose more money than they really need to? Those extra, unnecessary losses eventually hurt other workers and what's humane about that? Moreover, as employees drift away from a doomed plant during the notification period, the factory becomes even less viable and more difficult to sell. Again, others are hurt and what's humane about that? Likewise, once Congress mandates advance notice of 60 days, what's to keep the lawmakers from extending the period and trying other ways of telling management how to do its job?

In any event, the plant closure provision should stand or fall on its own merits instead of being tied to a measure designed primarily to help combat unfair practices by America's foreign competitors.

Even if this provision is eliminated, there are still plenty of other flaws in the trade bill that would warrant President Reagan's vetoing it. Among those flaws are the bill's many favors to special interests, often at the expense of American consumers. These favors generally enable certain businesses to reduce their costs for foreign-made supplies or ease their marketing of goods made abroad.

Perhaps the most flagrant giveaway worth about $100 million was slipped in, without benefit of hearings on its merits, for Warner-Lambert Co. Its patent on Lopid, a lucrative cholesterol-reducing drug, is due to expire in July 1989, when generic drug firms could produce it at lower prices. Instead, the new trade bill would extend Warner-Lambert's patent for three and a half years. The favor to Warner-Lambert would mean needlessly high costs to patients and to taxpayers, who pay for the drug through Medicare and Medicaid.

Though Congress has been tinkering with the trade bill for two years now, it still falls so far short of the mark that President Reagan should have no qualms about vetoing it.