Philosophers have long worried about the problem of knowledge, and created an entire discipline, called epistemology, with the aim of sorting it out. This week one Birmingham residential scheme cut through three millennia of confusion to come up with an answer.

The resolution to an arcane dispute about when you can know whether or not something is a risk to something else has allowed a 480-unit Birmingham residential scheme to go ahead, despite city council objections.

Birmingham City Council’s planning committee was told that opposing Eutopia Homes' £130M scheme at Camp Hill was likely to be pointless, and now both a government planning inspector and housing minister Robert Jenrick have agreed.

The dispute turned on the exact point when it would become clear whether the scheme did, or did not, pose a knowable threat to a rail improvement scheme.

The decision, published here, comes as the city’s planning system faces increasing strain.

Recent controversies include confusion over what is permitted in conservation areas, disarray over policy on tall buildings and uncertainty about affordable housing targets.

The Eutopia Homes scheme was rejected by the city council largely on the grounds that it might prejudice work on the Camp Hill Cord rail improvement. The cord is intended to reopen the Camp Hill line for passenger services from Tamworth/Nuneaton to run into the new platforms at Moor Street Station. Viaducts in Bordersley will help take the strain off busy New Street station.

Advising the council when it took its initial decision last year, Birmingham’s interim director of inclusive growth said that the basis upon which the council might refuse the application was “very slim” and that to withhold consent “wouldn’t be a reasonable position from the planning point of view”. During evidence to the planning inquiry a council planning official agreed that the site should have been granted consent.

The council’s case collapsed at the point where it admitted it had no objective reason to suppose developing the site would actually prejudice the Cord proposal, and instead merely thought there was a chance it might not help it. The inspector summed this up as a case “expressly on the basis that there was no evidence of absence of future prejudice”.

The inspector concluded it could take four years or more for the final alignment of the cord to be agreed, and therefore at least four years before anyone could know whether or not the site would cause a small problem, or a large problem, or no problem at all.

“There is simply no justification for sterilising the appeal site for (at least) four years until a final alignment [for the Cord] is defined…and where all of the evidence demonstrates that an effective scheme for the Cord could in fact come forward,” the planning inspector said in her report.

The minister took the point further. “It is agreed by all parties, that the extent of any land take required to deliver the south-west cord cannot be determined presently with any degree of certainty. For the reasons stated the Secretary of State agrees with the inspector … that it cannot be said definitively, at this point in time on the evidence available, that the appeal scheme would or would definitely not prejudice delivery of the cords,” the minister said in his decision letter.

The city council escaped a substantial award of costs against them, the minister and the inspector agreeing that the council’s decision did not constitute unreasonable behaviour.