There are certain emotions that are subject to external scrutiny. For example, if someone does not feel grief at the loss of a loved one or fear in the face of danger, it suggests that something is awry.
But Michael Hand and Joanne Pearce, of the Institute of Education in London, argue that while mentally healthy people are expected to express love towards at least one element in their lives, it is not necessarily assumed that this element should be their country.
In their role as guardians of children's wellbeing, teachers are expected to guide pupils away from loving anything that might be corrupt, depraved or detrimental to them.
"And there's the rub for patriotism," the academics say. "Countries are morally ambiguous entities. It is hard to think of a national history free from the blights of war-mongering, imperialism, injustice, slavery and subjugation."
The researchers then spoke to teachers and pupils from 20 secondaries around London. They found that fewer than 10 per cent believed that schools should actively promote patriotism. One history teacher told researchers: "It reeks of the old British empire."
Only one in five teachers that the institite's researchers surveyed believed that they should even support patriotic views expressed by pupils. A citizenship teacher said: "Praising patriotism excludes non-British pupils. Patriotism about being British divides groups along racial lines."
Most teachers felt they had an obligation to point out to pupils that patriotism can lead to less-than-noble sentiments.
"There is a propensity for jingoistic-type thinking to come through," one said. "I think it's a really dodgy subject to teach."
Indeed, while the aim of teaching patriotism is to unite pupils in love for their country, the lessons can have the opposite effect. Many Afro-Caribbean pupils, for example, feel defined by their Caribbean heritage, and express greater patriotism towards Trinidad or Jamaica than towards Britain. The researchers conclude that patriotism should ideally be taught as a controversial issue, open for discussion.
They said: "Recent calls by political leaders for the promotion of patriotism in schools lack a sound philosophical justification, and run counter to the views of most teachers and students."
Not all patriots are card-carrying, flag-waving zealots or face-painted bigots, according to many of those who support the teaching of Britishness in schools.
At Civitas, a right-wing think-tank, Anastasia De Waal believes that the image of patriotism suffers because it is mistakenly confused with nationalism.
"We're slightly squeamish about patriotism," she says. "With any nation, there are going to be negatives. But it's better to disclaim them and look at the positives. You don't have to discuss everything.
"The problem with leaving everything open to debate is that you end up with no position at all."
But national pride need not be taught directly. George Courtauld, author of the Illustrated Book of Patriotism, describes lessons in the subject as "sinister". But, he says, a love of Britain can be inculcated through well-taught history lessons.
"There's a lot of apologising for episodes in Britain's past," he says. "We teach about slavery, but the fact that it was the Royal Navy that stamped out slavery often isn't mentioned. Children don't know who Nelson is.
"If we talk about outstanding figures at school, pupils can say, 'I'm so proud of Shakespeare or Florence Nightingale'."
Tony Breslin, chief executive of the Citizenship Foundation, agrees that schools should help pupils to develop a sense of national identity.
"Of course you can teach patriotism," he says. "White, working-class boys sometimes feel they don't have any ethnicity. That's one of the myths that needs to be corrected in the classroom. You create a space where myths are challenged and facts put on the table."
And he denies that lessons in patriotism will alienate pupils from different national heritages: "That's patriotism, too. There might be several patriotisms at play in any one diverse classroom."
Ms De Waal agrees. She points out that citizens of the United States are able to describe themselves as Italian-American or Greek-American without compromising their national loyalty.
"Pupils are growing up in a complex democracy," says Mr Breslin, "so you need the legal, social and economic skills to become an effective citizen.
"You need them to understand how it is and isn't appropriate to put that into play in a modern democracy."