A spectre has been haunting universities:

the spectre of Moocs, or "massive open online courses". They are web-based programmes offered by academics and aimed at wide audiences of learners, usually with no prior qualifications needed. As befits spectres, Moocs evoke strong reactions.

Some fear the good old ways of classroom education are being undermined while others hail these courses as the saviour of tertiary education. Others argue that, just five years since their introduction, Mooc fatigue is already setting in and we should be looking beyond them.

Having spent the past few months developing a web-based course on international law at the University of Glasgow, I think there is great interest and excitement in the concept of free online learning. Several Scottish universities, including Glasgow, have signed up to the UK-led platform FutureLearn, offering a wide variety of subjects that are already proving hugely popular. My course, Right v Might in International Relations launches on Monday and offers an opportunity for anyone to learn, discuss and engage with regard to some of the most important legal issues of our time.

But where are Moocs leading us? So far, there is little evidence of regular education being pushed aside. While experimenting with online courses, many Scottish universities have expanded on-campus teaching, especially at graduate level. It would seem Moocs are designed to complement, not replace traditional modes of education, and that is where they hold real promise.

Online access education permits academics to engage with much larger groups of students. Prominent US courses on questions with broad mainstream appeal, such as Michael Sandel's course on justice, perhaps the most successful so far, are taken by upwards of 100,000 participants.

Our online course on international law, with much less marketing and a much more specific focus, has already seen several thousand sign up. These numbers are a challenge. Where understanding cannot be simply tested by multiple-choice tests, they practically exclude time-consuming forms of examination.

Who would volunteer to mark thousands of scripts? Similarly, online forums, a key aspect of many Moocs that allows participants to discuss key questions (can states use drones against terrorists or why does America operate a naval base in Guantanamo?) require robust monitoring. But these courses' mass appeal is a huge opportunity.

That 100,000 people across the globe should follow a course on justice taught by a Harvard professor is fascinating. My colleagues and I are excited at the prospect of discussing Guantanamo Bay, or the legality of drone strikes.

And more generally, Moocs may be an opportunity for universities to foster public debate and engagement across all age groups and with those who have no qualifications, some or many.

These are powerful arguments for supporting the development of more broad-based courses that open up higher education to all. Lest this be seen as a one-way street, universities also stand to gain from reaching out: many are consciously using Moocs to raise interest in on-campus courses; some are beginning to experiment with smaller, fee-paying online courses; and an agenda is being set that will blend traditional and online learning with a mixture of written and internet sources.

The experience will no doubt be filtered back into, and help improve, the way in which students will be taught in the future.

All things considered, universities have little reason to feel haunted by Moocs. They are an exciting new form of education that has the capacity to complement on-campus courses. Massive open online courses will neither save higher education nor overwhelm it. But they have the potential to enrich it. Don't take my word for it. Sign up for Right v Might and make up your own mind about Moocs.