It was hard enough four years ago to discern the point of these empty exercises in film-clip hagiography and ideological self-congratulation. The networks had rightly given up full-scale coverage because the conventions had become, as one exec complained, “an endless sea of blah.” The nominees already signed, sealed and delivered, the platforms set to music in private meetings and focus-group reports, the Republican and Democratic conventions seemed to be of interest to no one but placard manufacturers, local caterers and demonstrators.

And that was even before two groups, one foreign, one domestic, threatened to undermine all that these gatherings are meant to stand for. On the home front, the corporations and lobbyists have moved in, emboldened by changes in the law that provide a sneaky subversion of campaign-finance reform. Cocktails, dinners, outright donations: the host committees for the conventions will rely on more than $100 million in largesse from such interested parties as pharmaceutical companies, defense contractors and media conglomerates. That’s more than 12 times the 1992 figure.

If only soft money made tax dollars unnecessary. But fears that the conventions constitute an obvious terrorist target have pushed the bill for security to unprecedented levels. Congress inched up on an aid number until finally $100 million was allocated. Your tax dollars at work to make it possible, among other things, for police officers to screen subway commuters in New York or stop Boston motorists trying to go anywhere near the Fleet Center. If you live in either city, you get double-dipped: pocket-picked and searched both at the same time.

Where’s the payoff? Well, city leaders always argue that hosting the conventions will boost business and image. But a public-policy group at Suffolk University actually estimates that Boston will wind up losing money on the convention, and that New York’s windfall will not be nearly as large as predicted. David G. Tuerck, the economics professor who runs the Beacon Hill Institute, says it’s hard to assess the true cost to a city; Boston, for example, lost two major events because of its decision to host the Democrats, while the Republicans have been loath to share information about their cost estimates.

Certainly boosters are prone to late-summer amnesia where conventions costs are concerned. Los Angeles found itself four years ago recovering from a Democratic convention that forced the city to eat millions of dollars in overruns. As for the exposure a political convention brings, please. New York is the greatest city in America and perhaps the world, and Boston is one of the great intellectual crossroads and a birthplace of modern democracy. Neither needed to be transformed into an attractive nuisance for terrorists for the sake of image or even hotel occupancy.

The conventions will include none of the much-needed substantive discussions about issues, about health care, the direction of the economy, the scope of civil rights and our place in the world. There is no suspense about the outcome, as there was when John F. Kennedy slugged it out with Estes Kefauver for the second spot on the ticket or the Democrats went wiggy in Chicago. Many people in the host cities are inconvenienced, this year significantly so. With street closures for blocks around convention venues, stores will lose much of their commerce. And in the interests of civic dermabrasion, both cities will deny their true selves. Last time out, New York tried to disappear the homeless and the hookers. This time, it’s trying to do something similar with demonstrators, in a town that normally eats dissent for dinner.

So let’s recap: the business of both political conventions, such as it is, could now be taken care of in one day or, better yet, on-line. Corporate conventions could take their places, generating as much, if not more, in revenues. This would save taxpayers millions of dollars in security costs, protect small-business owners in the area of convention centers and save city residents from massive hassle. It would also curtail yet another area in which big companies attempt to mold the political process through big money.

Instead, the leaders of New York and Boston have allowed the political parties to paint a bull’s-eye on their towns for terrorists. And for what? An infomercial for a product most viewers have already decided to purchase or reject. The undecideds won’t be wooed by balloons, confetti and carefully edited oratory. While public housing crumbles, soldiers lack equipment and the elderly ration their own drugs, we spend a fortune on sound and fury, signifying nothing much. Why?