Like many people, I have personal experience of the NHS. In my case, medical care, personal life and scientific life are all intertwined. I have received a large amount of high-quality NHS treatment and would not be here today if it were not for the service.

The care I have received since being diagnosed with motor neurone disease as a student in 1962 has enabled me to live my life as I want, and to contribute to major advances in our understanding of the universe. In July I celebrated my 75th birthday with an international science conference in Cambridge. I still have a full-time job as director of research at the Centre for Theoretical Cosmology and, with two colleagues, am soon to publish another scientific paper on quantum black holes.

Jeremy Hunt can attack me all he wants – but he is wrong to say the NHS is working | Stephen Hawking Read more

Last year my personal experience of the NHS and my scientific life came together when I co-signed a letter calling for healthcare policy to be based on peer-reviewed research and proper evidence. The specific issue addressed in the letter was the “weekend effect”. Jeremy Hunt, the health secretary, had claimed that thousands of patients died unnecessarily because of poor hospital care at the weekend, and used this to argue that we needed to implement a seven-day NHS. I had mixed feelings about the issue. Having spent a lot of time in hospital, I would like there to be more services available at weekends. Also, it seems possible that some patients spend more time in hospital than is necessary because certain diagnostic tests can only be done on weekdays.

However, as we showed in the letter, Hunt had cherry-picked research to justify his argument. For a scientist, cherry-picking evidence is unacceptable. When public figures abuse scientific argument, citing some studies but suppressing others to justify policies they want to implement for other reasons, it debases scientific culture. One consequence of this sort of behaviour is that it leads ordinary people to not trust science at a time when scientific research and progress are more important than ever.

This problem goes beyond the weekend effect. The NHS is in a crisis, and one that has been created by political decisions. These political decisions include underfunding and cuts, privatising services, the public sector pay cap, the new contract imposed on junior doctors, and removal of the student nurses’ bursary. Political decisions such as these cause reductions in care quality, longer waiting lists, anxiety for patients and staff, and dangerous staff shortages. Failures in the system of privatised social care for disabled and elderly people have placed an additional burden on the NHS.

So what is to be done? A physicist like me analyses a system in terms of levels of approximation. To a first approximation, one can see the situation facing healthcare in this country in terms of forces with different interests.

On the one hand, there is the force of the multinational corporations, driven by their profit motive. In the US, where they are dominant in the healthcare system, these corporations make enormous profits, healthcare is not universal, and it is hugely more expensive for the outcomes patients receive than in the UK. We see the balance of power in the UK is with private healthcare companies, and the direction of change is towards a US-style insurance system.

When public figures abuse scientific argument to justify policies, it debases scientific culture

On the other hand, there is the force of the public, and of democracy. Opinion polls consistently show a majority in favour of a publicly provided NHS, and opposed to privatisation and a two-tier system. Therefore, the best way to support the NHS is to empower the public. There are two priorities. First, clear information that public provision is not only the fairest way to deliver healthcare, but also the most cost-effective. Second, a loud voice and the political power to make politicians act on our behalf.

If that all sounds political, that is because the NHS has always been political. It was set up in the face of political opposition. It is Britain’s finest public service and a cornerstone of our society, something that binds us together. People value the NHS, and are proud that we treat everyone equally when they are sick. The NHS brings out the best in us. We cannot lose it.

• Stephen Hawking, the author of A Brief History of Time, is director of research at the Centre for Theoretical Cosmology at the University of Cambridge, where he was Lucasian professor of mathematics