No sooner had I said in a Times ÖйúAƬ blog that life is much more pleasant in a US university compared with most British institutions than three professors at the University of Alabama at Huntsville were murdered, allegedly by an unhappy colleague whose application for tenure had been turned down.

It is one of the innumerable oddities of the US that although the level of assaults is - perhaps surprisingly - a lot lower than in the UK, such attacks are much more likely to be fatal. The reason, of course, is the easy availability of firearms.

The aggrieved professor, who is alleged to have killed three of her colleagues and seriously injured three more, stopped shooting only because she ran out of bullets. The mentally ill young man who killed 32 students and faculty at Virginia Tech in 2007 had equipped himself more thoroughly for a massacre.

Whatever these incidents provoke, it won't be a tightening of the legislation that controls - where it does - access to handguns and heavier weaponry. In the academy, there may be more background checks on faculty when they are recruited, and a temporary increase in the counselling offered to scholars who are denied tenure; what there won't be is an attempt to reduce the amount of weaponry in circulation.

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During the presidential campaign of 2008, Barack Obama went out of his way to persuade voters that he had no intention of taking away their guns.

If anything, the enthusiasm for arming oneself to the teeth is increasing. In Texas, Debra Medina, a conservative candidate for the office of governor, is campaigning against the restrictions on carrying concealed weapons that prevent her hiding a loaded pistol in her handbag when she goes to the grocery store.

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New Yorkers treat all this with a grimace and a shrug, but Texas is the second-most-populous state in the US and is growing faster than any other, so the policy isn't an entirely harmless piece of lunacy.

In fact, it is one aspect of what looks like mass hysteria, exemplified by the so-called "Tea Party movement", one that seems to have seized a sufficient number of members of Congress to paralyse the federal government at a time when the country urgently needs decisive policies to control the financial industry and make the healthcare system something other than a sick joke.

It is true up to a point that the Republican Party has adopted the outlook of German communists when Hitler came to power: "nach Hitler, uns", they thought - "after Hitler, us". But Republicans don't just reckon that if they paralyse Washington, they will discredit Mr Obama and regain power; they, too, are terrified of fired-up populists whose hatred of government of all kinds may help them defeat the Democratic administration, but will then make their lives impossible in turn.

The present problems have very deep roots. Ordinarily, I admire James Madison, the chief architect of the American Constitution, to the point of idolatry. But some of the devices he built into the Constitution agreed in 1787 are turning out to be disastrous; and the decision not to adopt a parliamentary system of government has been revealed as a mistake. It's no surprise that of the almost 200 constitutions drawn up since the Second World War, only one follows the American pattern, and that's the Philippines'.

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Madison was immensely sophisticated, well read and subtle, but he was not the founder of "American democracy", and in fact did not want a democratic US. Although he relaxed in later life, he was initially afraid that if the lower classes had the power that a democratic Constitution would give them, they would short-sightedly attempt to exploit the better-off, and improve their own position, by debauching the currency or legislating to repudiate their debts and those of their states.

So, the Constitution was designed to prevent the demos - the people Aristotle described as "the poor many" - from exercising the sort of power they would have exercised in a simple, unicameral majoritarian democracy. Initially, president and Senate were indirectly elected. The residue of that system is that the president has no direct influence over Congress; the idea that a party with a programme and a majority can just get on with it is a nightmare to some and a distant dream to others. Gordon Brown would have apoplexy.

And the Senate, which even Alexis de Tocqueville, visiting in the 1830s and with all the prejudices of an aristocratic young Frenchman, thought of as just the sort of calm, intelligent, public-spirited deliberative assembly that Madison had intended, is now a complete disaster.

To get the Constitution agreed by all the original states, Madison had to build in equal representation, not for individuals but for states. Each state has two senators, whether it is Wyoming - population half a million - or California - population 36 million. Most of the smallest states are rural, religious and remote; they have no sympathy with the plight of big cities and industrial agglomerations, let alone the sophisticated secular culture of such places. But their senators can and do hold legislation to ransom, blocking healthcare reform, demanding payoffs that madden the populists and make the liberals despair.

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So, any academic in the US worried that an unhappy colleague may be coming to work with a handgun would be ill-advised to hope that legislative common sense will break out any time soon.