While the reasoning seems sound, it lacks conclusive data. It is yet to see a study that shows that sickly individuals reproduce as well as the healthy, and there are plenty of reasons to believe that they might not. Measures of attractiveness are subjective anyway and tend to change over time. Also, studies measuring the reproductive rate of different intelligence cohorts of our society tend to rely on unreliable measures that are tinged with racism. It would still be argued that the jury is still out on whether any of these factors currently affect reproductive success.
Much more important, however, is that, even if 100% accurate, the reasoning above would only argue that natural selection is no longer at work. It has been researched that a population can continue to evolve even when selective pressures are removed because selection is not the only force in evolution.
The only way it could be true that the human species is no longer evolving is if rates of successful reproduction were spread evenly and randomly among all possible segments of the population. We know that this is not the case.
First of all, birthrates are much lower in wealthy countries than they are in developing ones and are continuing to fall. The population in Japan is currently shrinking, and so would the population of several Western European countries were it not for immigration. This means that the contribution of the Japanese, Italians, and Spanish to the future gene pool of the species is getting smaller and smaller. That’s evolution.
Secondly, within a given country, whether developed or underdeveloped, some people reproduce more than others and this is not purely random. Those of higher socioeconomic status have better access to birth control resources, tend to choose the smaller family size, and are also more likely to forgo reproduction altogether. Therefore, those of lower socioeconomic status tend to leave more offspring. That’s evolution, too.
Besides economics, things like religion, education level, career advancement, ethnic and family background, and even political beliefs all affect reproductive rates. In the West, these many factors influencing reproduction do not break down evenly across the various racial groups because of the long history of racial oppression and ongoing social and political inequality.
So this wholly means that, in North America and Western Europe, people of African and Latino origin tend to have more children than nonimmigrant Caucasians, on average, but even this trend is not uniform and there are strong regional differences. In Asia, there are wide differences as well. Large families are completely unheard of in China, Japan, India, and most of Southeast Asia, while countries like Pakistan, Iran, and Afghanistan have sky-high birthrates.
The point is that evolution occurs in a species whenever there are differences in reproductive success. That is certainly the case with humans right now. It has been researched and it’s true that differential survival is not a major phenomenon, at least not in the developed West, but differential reproduction certainly is. It doesn’t matter that the differences are due to conscious reproductive choices. It’s still an unequal reproductive success. That’s evolution.
Humans are evolving. In what way we are evolving is harder to answer, and is constantly changing anyway.
The only constant in life changes.