Seen from one direction, the visit of Daniel Taub, the Israeli ambassador to the UK, to the University of Glasgow looked like an exercise of free speech by a controversial figure in a democratic country.

From another, with a helicopter hovering overhead, a police presence on campus, and students protesting outside, it looked like a controversial decision being imposed by force. But it was absolutely right that Mr Taub's visit went ahead.

A group of academics at the university take the opposite position. In a letter to The Herald, more than 20 academics in education, law, sociology and other disciplines say they are saddened by the visit and that the invitation should not have been extended to Mr Taub. Israel, they say, has effectively silenced legitimate expression by Palestinians through limiting their movement, appropriating their land and violating their rights and, by inviting Mr Taub to speak, Glasgow University has taken the side of a powerful aggressor.

The letter writers also have some more practical objections to the way Mr Taub's visit was handled. They say it was organised secretly and the identity of the speaker was not announced in the days leading up to the visit, which meant students did not have all the information they needed to make a decision about whether to attend or indeed to take part in protests against the visit.

The practical arguments of the academics are reasonable. There are obviously security implications in the visit of an Israeli ambassador to a British university campus, but the university authorities should be open and honest about who is coming and why in order that student or campaign groups have the time to exercise their right to peacefully protest against the visit.

The arguments around the principle of Mr Taub's visit are much trickier. The protesters assert that Israeli institutions and their staff should be boycotted on the grounds that Israel is an occupying power which refuses to adhere to international law and they absolutely have the right to make that argument and target their dissent directly and loudly at Mr Taub and others. But Glasgow University must also have the right to invite Mr Taub to speak on the grounds that their students should have access to a range of perspectives on important issues. Both positions should co-exist and neither must be allowed to dominate.

If the voices calling for boycott prevail, the results can be seen in the regrettable case of Israel's Incubator Theatre which had to pull out of its planned run of performances at the Edinburgh Festival Fringe last year in the face of protests. The theatre group was a perfectly legitimate target for dissent and protest, but they should have been able to go ahead in the face of it.

The same principle must apply on a university campus. If a university invites a leading representative of a state that is pursuing controversial policies such as those in Gaza, it should expect, and facilitate, loud and angry protest. But the protesters should not expect to be able to close down the alternative position. Dialogue and protest are better than no dialogue at all.