Analogy, Freud remarked, is the weakest form of reasoning. It is also the way most people think, most of the time. And it is most of what passes for knowledge in discussions of politics.

So drawing analogies between British and American politics is natural. After all, we are both English-speaking democracies with a common law tradition.

The weakness of analogy derives from our innate focus on the similarities rather than on the differences between the situations being compared.

Allow me to illustrate with a game. Imagine four cards, each with a letter on one side and a number on the other. On the sides you can see, two have letters, E and K, and two have numbers, two and seven. Which two cards would you turn over to test the claim “if a card has a vowel on one side it has an even number on the other”?

Try it before reading on.

If you are like three-quarters of experimental subjects, you selected the vowel (E) and the even number (2), similar to the instruction. The correct answer (E and 7) requires us to look at differences as well.

With that spring diversion in mind, let’s understand some of the fundamental differences between our situation and theirs before internalizing too many lessons from Tony Blair’s historic victory.

Start with the fact that Blair only had to garner 35 percent of the vote to win in this multiparty field. Undoubtedly, Blair would have won a two-party smackdown, but that’s just the beginning.

Blair was also an incumbent with a strong economic record. While other countries have suffered recession, Blair’s Britain has enjoyed a dozen consecutive years of economic growth.

In addition, Labor benefited from a long-term Tory collapse. While Democrats and Republicans are at parity in the United States, Labor has held a 13- to 17-point lead in party identification for years. Ideologically, the United Kingdom is evenly split between left and right. In the United States, conservatives outnumber liberals by 13 points.

Those political differences reflect divergent underlying value orientations. Americans are religious, individualist and anti-statist and lack class consciousness. Britons are secular and pro-state and exhibit greater class allegiance.

As this column regularly reiterates, religiosity has becoming an increasingly potent factor in a nation where 42 percent of the electorate claims to attend church at least weekly. Not so in Britain, where that number is less than 17 percent. Nearly all Americans believe in God; less than half of Britons do.

While the political significance of social class is declining in both countries it remains a more salient influence in Britain, where more people identify as working class than as middle class. That’s in stark contrast to the American situation, where only 22 percent identify as members of the working class, compared to half who consider themselves middle class.

Britons are about twice as likely as Americans to favor government policies to narrow the gap between rich and poor.

Sept. 11 was more deeply etched in the American consciousness, producing a dramatically different issue agenda. In the United Kingdom, just 3 percent identified the war on terror as a top voting issue, compared to 19 percent here. Moreover, for some years Labor has been seen as better able than the Tories to protect the country from terrorism — a far cry from our plight.

Healthcare was the most important issue for government in the British election. Not here.

Iraq also played differently. While a majority of Americans now believe the war was not worth the cost, that was not the case last November. Going into the British election, voters there thought the war was not worth it by at least a 10-point margin.

Perhaps the differences tell us more than similarities.

Mellman is president of The Mellman Group and has worked for Democratic candidates and causes since 1982, including Sen. John Kerry (D-Mass.) last year.