Transhumanism is the philosophical and cultural movement that holds that human beings should use technology to improve their physical and cognitive capabilities beyond their current biological limits, potentially indefinitely. Its leading philosophers, Nick Bostrom, Max More, Aubrey de Grey, argue that the traditional biological parameters of human life (limited intelligence, limited health, limited lifespan, limited emotional control) are not sacred has to be preserved but contingent limitations to be overcome, just like other limitations humans have always tried to overcome.
The transhumanist argument has a certain straightforward logic. We regard it as good to cure cancer, correct vision, treat depression, and extend healthy life expectancy. All of these involve improving on the baseline biology we're born with. So what principled distinction exists between treating a disease (which everyone approves of) and enhancing beyond normal function (which many people feel uneasy about)? If it is good to raise a person's IQ from 70 to 100 by treating the cause of intellectual disability, why is it not equally good to raise it from 100 to 130 by other means?
This is the therapy-improvement distinction, and it is philosophically less stable than it looks. The sociologist and philosopher Carl Elliott and others have argued that the distinction does important moral work in our intuitions even though it is hard to define precisely. Part of the discomfort with improvement is not that it produces better outcomes but that it changes the relationship between effort, character, achievement, and identity in ways that matter morally.
Here is one way to see why. Imagine two athletes. One trains obsessively for years, develops exceptional discipline and resilience alongside their physical ability, and wins an Olympic gold medal. The other takes a pill that produces identical athletic performance without the training. Both win. Is the second athlete's win equivalent to the first's? Most people feel some resistance to saying yes, and that resistance is not simply about cheating (suppose the pill is legal). It has something to do with the relationship between the achievement and the person achieving it. The pill winner has an outcome; the trained winner has a story.
Michael Sandel makes a related argument in The Case Against Perfection (2007). The drive to improve is connected to a deeper cultural imperative he calls hyperagency: the demand that everything about us be the product of deliberate choice and optimization, that nothing be left to chance, luck, or nature. This imperative, he argues, corrupts certain virtues that depend on accepting what is given: humility, solidarity with those less fortunate, appreciation for the unchosen. A world of comprehensively improved people might be a world of individually better people who collectively cannot accommodate limitation, loss, or the ordinary human condition.
On the other side, the disability studies philosopher Rosemarie Garland-Thomson and others argue that discomfort with improvement is sometimes, if not always, a disguised discomfort with difference, that anxiety about changing human nature often encodes a preference for a narrow conception of normal humanity that itself has a problematic history. The question of what counts as "enhancing" versus "normalizing" is deeply politically charged.