Few political questions provoke as much passion as the extent to which private companies are allowed to deliver public services. Witness the furore over "back-door privatisation" of the NHS, say, or the accusations of inefficiency and waste flung at public sector "bureaucrats". The truth is, of course, far more complicated: amid the vast array of state-run services, some may be ripe for competition, others less so. What cannot be in doubt, however, is the merit of focusing on the quality of the service itself, rather than how – or by whom – it is delivered.

Probation is the latest candidate for an injection of market forces, and today saw the Justice Secretary set out plans for non-state organisations to take on low-risk offenders. Notwithstanding the dangers of badly designed "payment by results" schemes skewing priorities and wasting taxpayers' money, with recidivism rates so high and such scant assistance currently provided to the majority of those leaving jail, the plan has much to recommend it.

Introducing the profit motive into state education is a more complex proposition altogether. The creation of, first, academies and, then, free schools already allows for institutions not run by the local council. Now, as The Independent reports today, a think-tank with close links to David Cameron wants to relax the rules further and allow profit-making companies into the sector. In fact, the plan is expected to be in the Conservatives' 2015 manifesto.

Proponents claim that profit-making schools are a natural next step, enabling companies with deep pockets and professional resources to take on the tricky business of finding sites, building facilities and bearing the risk of failure. Meanwhile, critics warn of high costs, slipping standards and educational institutions with their eye on the wrong ball. There are certainly plenty of potential pitfalls; developments must be gradual and scrutiny relentless. But the proposal should not be dismissed out of hand. In education as in probation, public services must be about practicality not ideology.