Good to hear from you again John, thanks for your comments. I think the main problem is that we don’t know if IQ tests do indeed offer “an objective view about mental performance” because the research linking entrance test performance and ability to perform at school has not been done. Those who have been trained to perform better on the entrance test do not necessarily then perform better in school – they have likely been trained to do a very specific type of problem that may have little relevance to school studies. The other problem for me is the stress and anxiety that these tests can cause, particularly for those who do not get in.

I’m interested in your comment about grammar schools having a more intensive academic delivery system. As someone who went to a grammar school, I didn’t feel that it was particularly intensive. We had sets with students separated according to their ability; not all students were given the same level of delivery. I can only compare this with the non-selective secondary schools that I’ve spent time in as a researcher, but overall I haven’t noticed any differences in delivery. It would be interesting to find out more about what actually differs in teaching practices between grammar and non-selective schools.

I agree that we need to accept the importance of both nature and nurture, and ideally use what we know about the impacts of nature and nurture to guide practice in the classroom (for example, through precision education in the future).

It is well known by teachers working in areas where selection for grammar schools remains that, just as you write, “IQ fluctuates, and individuals can be trained to perform better on IQ Tests.“ This is the precise reason why parents pay for private tutors to prepare their child for taking the test and why schools are restricted in the extent to which they can prepare children in school time. The grammar school system is predicated on the idea that it is possible to give a numerical value to intelligence and that intelligence is fixed, thus justifying selection at 11+. That said, I still disagree with your view that “sorting on this basis may not serve any useful purpose.” It is at least offers an objective view about mental performance, even if it fails in regard to its robustness over time and it serves the precise purpose of differentiating, at a given point, those students who seem to have capabilities that grammar schools recognise are required for their more intensive academic delivery system.

The assumption that some individuals have higher intelligence than others in fact describes a truth that has been evident throughout human history. It may be an idea that is uncomfortable to entertain, but it is nonetheless true. We are no more equally intelligent than we are equally tall, sporty, artistic, etc. If we accept the premise that both nature and nurture contribute to our makeup in different ways, to a different extent and at different times in our development then plastic intelligence accounts for the different outcomes.