I'm still not sure what to think. Should we be thoroughly depressed that the headlines are dominated by Jew hatred? Or ought we to be relieved that it is out in the open?

But important as it is that individual cases are exposed, in some ways they miss the point. Because the current crisis for Labour is not the result of a few isolated racists being caught out. It's that the mindset and political outlook of the group that is now in charge of Labour is founded on the idea that Israel is the enemy. And it's a short hop from that to Jews being the enemy.

For three decades, Jeremy Corbyn existed on the political fringe, surrounded by and speaking only to fellow extremists. No one cared what he said or thought. He was an irrelevance. But now, he is leader of the Labour Party. Every word he has ever uttered, every thought he has ever shared matters - because he could be Prime Minister.

So now it really matters that we understand those fringe ideas. It matters that we understand how he can come to describe representatives of Hamas and Hezbollah - organisations that boast of their aim to kill all the world's Jews - as "friends". And it matters that we understand why he and his allies focus almost exclusively on Israel - which just happens to be the Jewish homeland - as the target of their hatred . So no matter what abuses may be carried out by the likes of China, Zimbabwe and Saudi Arabia - objectively and in number far beyond any mistakes made by Israel - it is only Israel that is the target of the boycott movement, of which Mr Corbyn has been such a vigorous proponent.

Jeremy Corbyn's strand of Labour politics defines itself as "anti-imperialist" and believes that the West - specifically, the USA - is the source of all the world's ills. In the fight against oppression it is the leading subjugator. After Vietnam, that attitude was hardened. The Cold War kept it in check, with the Soviet Union the bigger worry for all except the USSR's fellow travellers - many of whom were, to complete the circular chain, part of that same strand of the left. Then, with the collapse of communism, that anti-US mindset widened into a more general anti-Western mindset.

Everything else springs from this, not least the idea that Israel, viewed as the West's colonial outpost in the Middle East, is the enemy. With Israel no longer a plucky underdog on the edge of extinction, it became a prime target of anti-imperialism. And when a supposedly progressive and anti-imperialist Palestinian movement emerged in the 1970s, backed ideologically and financially by Soviet anti-Zionism, the pattern was set.

Now, because the likes of Hamas and Hezbollah are battling against Israeli oppression, they are by definition "friends" - and we can overlook their commitment to the murder of Jews. To see where this leads, look at Mr Corbyn's astonishing circumlocution at Prime Minister's Questions on Wednesday. Invited three times by David Cameron to withdraw his description of the terror groups as "friends", the furthest he could go was to say he could never be friends with racists, and that if someone is racist they could never be a friend of his. But still he could not condemn Hamas as racist.

Labour's problem is three-fold.

First, the fringe that holds this analysis as being the key to understanding global politics now forms the party leadership.

Second, even if the broad mass of the party is not signed up to this pure version of the theory, enough of it has seeped into the mainstream to have warped the party's wider approach - as when Ed Miliband could, in his first speech as party leader, attack Israel's behaviour in Gaza without a single mention of any Palestinian terrorism.

And third, this is what tips from anti-Israel politics to antisemitism. So we hear repeatedly about how "Zionists" run the media and business, as if changing the word from "Jews" gives a free pass.

We can have all the inquiries we like, with all the condemnations we want. None of it makes the least difference, because Labour's hard left cannot change its entire ideological outlook. This is the real issue. This is how they think.