To open your mind to the possibility that the Scarborough subway extension is a good plan, you need to disregard the rhetoric of its supporters.

Their talk about the “wall of hate” that stands in the way of this borough getting what it “deserves” and similar irrational straw-man arguments they focus on, make it easier to dismiss the extension by association.

But if you disregarded the advocates and listened closely to city staff members during the transit debate on Tuesday, it was possible to discern the case for building the subway extension. The reasonable argument in favour is about a lot more than one subway stop and about a lot more than its supporters seem to appreciate.

It depends on a set of interlocking conditions — a huge list of “ifs” — and some key questions become whether the coalition of populists and penny-pinchers supporting this thing understand that and will actually deliver on all of them. So it’s all the more important to make the case plain.

One premise (hotly disputed by some opponents) is that the criteria for making a decision today may be different than in 2010, when Rob Ford first cancelled the originally planned LRT, and different than in 2013, when Karen Stintz re-cancelled it. Then, the LRT was much cheaper and the province had agreed firmly to cover all its costs and build it on a schedule that is much faster than the subway plan.

Now, TTC CEO Andy Byford says the cost for the revived LRT plan may be as much as $3 billion, and the delays and changes to construction timelines mean it would not open until 2026. Furthermore, subway advocates say it is unclear whether the province would uphold its end of the much-delayed deal on costs.

If all that logic holds, then we are left today with a choice between two similarly priced, similarly scheduled options (with intricate side disputes about which level of government might fund which variation). In isolation, the LRT argument is still compelling, because, while it would require an extra transfer for people going downtown, it also has more stops (including some in lower-income neighbourhoods) that would mean closer bus or walking access for more people and be useful for shorter local trips.

But what the city’s staff were saying — emphatically — on Tuesday is that the subway stop is not a plan that can or should be considered in isolation. Keesmaat emphasized that the extension is part of a proposed network, and if you removed any single part of it, you’d need to scrap everything and go back to planning square one.

That network includes the SmartTrack version of GO’s express rail plan, with five stops in Scarborough (including one in a neighbourhood the LRT would have served), with trains arriving every 8.6 minutes during rush hour. And there’s the 19-stop Eglinton East LRT extension from Kennedy station to U of T Scarborough, which will provide good, high-order local service to central Scarborough. There’s also the relief subway line Byford insisted remains the TTC’s highest priority, necessary to open up space on downtown-bound trains across the whole system.

If you build that network to serve a variety of local neighbourhoods and open up subway capacity, then the main job — the one job — of the Scarborough subway extension is to provide fast travel to and from one neighbourhood. And more precisely, to re-invent that neighbourhood.

Scarborough Town Centre is a mall with easy highway access, bus connections to other cities and some nearby government administrative buildings. It has a lot of parking. But there are only a few residential and office buildings within what you could call walking distance.

As Keesmaat said, the existing streetscape is full of flyovers and highway off-ramps and wide high-speed roads. The formerly industrial area doesn’t right now offer property values that make it worth developing. “The market isn’t yet ready for intensification,” she said.

The hope — the proposition on which Keesmaat seems prepared to stake her professional credibility — is that a fast subway connection to Kennedy and the rest of the city beyond it will be the flint needed to spark a fire under the area’s comprehensive redevelopment. She spoke of “transforming the characteristics of the street” — putting in a whole new “urban grid” to build a true city centre in the traditional sense. Keesmaat invoked Yonge and Eglinton as a point of comparison on social media.

That worthy redevelopment concept strikes me as much bigger and more ambitious than the entire transit plan. In addition to a subway stop, it would seem to require the kind of co-ordinated, well-funded, decades-long effort that Waterfront Toronto has been putting into the downtown lakefront.

So: a generation-defining, city-building redevelopment effort and multiple transit lines worth $15 billion to $20 billion. If both of those conditions are fulfilled — and if city council doesn’t strangle the rest of its priorities and obligations to do so — then it’s possible to imagine looking back in 50 years and thinking a subway extension was a wise investment.

It’s possible to imagine it. But is it possible to believe it?

To open your mind to the possibility, you need to disregard not only the rhetoric of the extension’s supporters, but their records. This gang’s history is one of cheaping out at every opportunity and rejecting virtually every new or increased tax proposal.

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Could the promise symbolized by a subway stop magically change them from skinflints to visionaries? It would be a political transformation as stunning as any physical one Keesmaat proposes.

The plan’s political proponents haven’t said anything to indicate that’s the case. My mind, however, is open to the possibility.