Theresa May’s Conference speech on Tuesday made some… strong claims about the harms of immigration, and attracted an array of excellent critiques in the media. I want to highlight one flaw that these reactions didn’t discuss in detail. Her argument relied on a constant blurring of the difference between the volume of immigration and the size of net migration flows. The problems she highlighted with immigration fall into two categories – problems with net migration, which generalise to population growth of any kind, and problems with the level of immigration - an influx of foreigners into our society.

She talked about immigrants putting pressure on government finances and education systems. Conspicuously absent was any mention of the fact that (unlike those of us who are scroungers born-and-bred), the majority of immigrants are actually net contributors to the state. Nor did she extend her logic to the hordes of babies and children in the UK who are net burdens on government services – perhaps because, like the children of immigrants, those children will grow up and pay taxes in the future.

The main thrust of the speech, though, focused on the social impact of immigration – the difficulty of creating a ‘cohesive society’ in the face of the 641000-strong huddled masses that came to the UK in 2014. May’s treatment of empirical research on the social consequences of immigration also leaves something to be desired. (For a more nuanced review of the literature, you might be interested in James Dobson’s ASI paper The Ties That Bind).

Approximately 330000 people moved to London in 2013 (including newcomers from elsewhere in Britain, as well as abroad). This is much higher as a percentage of the population than the 485000 outsiders that came to the country as a whole, and a much larger rate of social churn than in, say, the average town in the North-East of England. And yet the collapse of the social fabric has spectacularly failed to materialise. Indeed, London’s schools are better than elsewhere in the country and improving more rapidly, and there is substantial reason to believe that immigrants have a positive influence on this trend.

No one ever seems to worry about a tide of Scots flooding in and diluting our culture, destroying our values. But are they really like us in some fundamental way that French, Spanish and Polish graduates aren’t? Is there something in the water that hardworking Nigerian cleaners have failed to absorb?

The other assumption that went unexamined in May’s speech was that immigration is ‘high.’ There is some level of immigration at which the costs begin to outweigh the benefits. But with every wave of immigration, such claims have been made. In the 1930s: “Thousands of Huguenots were assimilated, but that was over the course of decades – there’s no way the country can cope with tens of thousands of Jewish refugees!” Each time, British society has proved its resilience and tolerance. Why would there be a sudden tipping point when immigration reaches about 1% of total population? There aren’t any compelling reasons to suspect that this time will be different – which might go some way to explaining May’s failure to provide any.