By the standards of the time

Racism was common in the women’s suffrage movement on both sides of the Atlantic. The American suffragette Carrie Chapman Catt said that: ‘White supremacy will be strengthened, not weakened, by women’s suffrage.’ Emmeline Pankhurst, her British sister in the struggle, became a vociferous supporter of colonialism, denying that it was ‘something to decry and something to be ashamed of’ and insisting instead that ‘it is a great thing to be the inheritors of an empire like ours’.

Why do so many find it impossible to believe that any so-called genius could fail to see that their prejudices were irrational and immoral? One reason is that our culture has its own deep-seated and mistaken assumption: that the individual is an autonomous human intellect independent from the social environment. Even a passing acquaintance with psychology, sociology or anthropology should squash that comfortable illusion. The enlightenment ideal that we can and should all think for ourselves should not be confused with the hyper-enlightenment fantasy that we can think all by ourselves. Our thinking is shaped by our environment in profound ways that we often aren’t even aware of. Those who refuse to accept that they are as much limited by these forces as anyone else have delusions of intellectual grandeur.

The classicist Edith Hall’s defence of Aristotle’s misogyny is a paradigm of how to save a philosopher from his worst self. Rather than judge him by today’s standards, she argues that a better test is to ask whether the fundamentals of his way of thinking would lead him to be prejudiced today. Given Aristotle’s openness to evidence and experience, there is no question that today he would need no persuading that women are men’s equals. Hume likewise always deferred to experience, and so would not today be apt to suspect anything derogatory about dark-skinned peoples. In short, we don’t need to look beyond the fundamentals of their philosophy to see what was wrong in how they applied them.
https://aeon.co/ideas/why-sexist-and-racist-philosophers-might-still-be-admirable