In 1909, the US satirical magazine Puck published an image that portrayed immigrants, quite explicitly, as vermin. In Samuel Ehrhart’s cartoon, Uncle Sam, a star-spangled pied piper, leads a scurrying group, carrying such labels as “murderer”, “thief” and “convict”, from the shores of old Europe towards the Statue of Liberty.

Rats remained a useful symbol for those who wished to portray their targets as inhuman for most of the 20th century. Most familiar and alien of all, perhaps, is the range of animalistic imagery that came to stand for Jews in the build-up to the second world war. In Der Stürmer, Nazi Germany’s most influential propaganda sheet, a cover image depicted a Nazi gassing Jewish rats that huddle around the base of a mighty tree. “When the vermin are dead,” the caption reads, “the German oak will flourish once more.”

On Tuesday, the Daily Mail ran a cartoon by Mac that, according to many online critics, played horribly into those bigoted associations. This time, the target was the refugees now arriving in Europe from the Middle East and North Africa. Mac’s cartoon refers to the fear that among the terrorists who struck Paris were some who had come to Europe as part of that mass migration. The image shows a crowd moving across a European border. One carries a suitcase, another a rolled-up bundle that could be a prayer mat or a sleeping bag. A man in silhouette appears to have a gun slung over his shoulder; a woman wears a hijab. And at their feet, in significant numbers but so small as to go unheeded, are a pack of rats. This was a deeply incendiary image. On Twitter it was described as “incitement to racial hatred” and “something from the days of the third reich”; the Huffington Post agreed that it was “straight out of Nazi Germany”.

But not everyone agrees - and those who work in the field, used to the way that an image’s immediacy can draw a voltage of fury that takes longer to build for the written word, are maybe inclined to a greater degree of sympathy for Mac’s intentions. “That wasn’t my reading of it at all,” says Nick Newman, the Private Eye cartoonist. “I think it’s been completely misinterpreted. I don’t think for a minute that Mac is saying that refugees are rats; he’s saying that terrorists are rats.” Anita O’Brien, curator-director at the Cartoon Museum, cautions that her view doesn’t mean she agrees with Mac, but also rejects the idea that the rats portray refugees in general. “They’re Isis fighters,” she says. “I don’t think anybody would have a problem with the idea that these people are despicable.”

Cartoonists have often come in for this kind of criticism: Gerald Scarfe, Dave Brown and this newspaper’s Steve Bell have all been accused of leaning on antisemitic imagery – dripping blood, baby-eating, puppeteers - when making points about Israel’s conduct. Your view of the validity of these claims is likely to depend on your view of whether such images rise to the level of trope - a persistent visual association that a casual viewer will have somewhere in the back of his mind - or are just part of the cartoonist’s general armoury that happens to have been deployed in a particular context.

“You cannot get away from the fact that, in cartoons, certain images have certain associations,” acknowledges O’Brien. “In the past, the rat has been an image. But I don’t think it’s been used so much recently. So I don’t think it means that the audience will draw directly on that, to conflate the rats with all refugees.” Others might ask whether that argument does enough to acknowledge the presence of the armed silhouette in the background. More generally, there’s the view of Chris Elliott, readers’ editor of the Guardian, who wrote in his assessment of the complaint against Bell’s “puppeteer” cartoon of Benjamin Netanyahu (which also cleared Bell of the charge of intentional antisemitism): “The image … echoes past antisemitic use of such imagery, no matter the intent.”

O’Brien’s word, “audience”, raises another question: context. According to Dr Nicholas Hiley, head of the British Cartoon Archive at the University of Kent, Mac’s work “probably looked fine in the Daily Mail, where the rats would be understood as terrorists hiding among the refugees. But when moved out of that context the imagery of rats and migrants gains a far more sinister appearance, uncomfortably close to the images of rats in Nazi antisemitic propaganda … The question is which of these contexts shows the true nature of the cartoon.”

Hiley refrains from answering his own question. In this morass, is it possible to adjudicate where the cartoonist’s heart lies? Is that even the point? Is collateral damage any less severe for being unintended, if indeed it is? These are questions that satire will always provoke, and the debate is probably healthier for being inconclusive. Still, if context is all, some might point to another recent image of Mac’s that drew similar, if less politically salient, opprobrium. After the news that Tom Jones planned a DNA test to discover if he had any black ancestry, Mac produced a cartoon that showed a travelling scientist, deep in the jungle, approaching a loinclothed tribesman holding a shrunken head and asking “just one more test ... can you sing Delilah?” The lineage of the description of black people as savages seems rather less subtle than the history of the cartoon rat. And if that piece of context isn’t enough to force the conclusion that yesterday’s image was blatantly racist, it may be nonetheless be relevant to those wondering whether Mac deserves the benefit of the doubt.