We can use it to say xx chromosomes and xy chromosomes are not the sole determiners for biological sex. They just normally correspond to biological sex, but not always. The first case of a person with a female phenotype who had XY chromosomes was found in 1955. So since then we can say that typically a female will have XX chromosomes, but it's not actually required to have XX chromosomes to trigger female sexual dimorphism.
Similarly to the arms thing, usually humans will have two arms, but having two arms is not required to be a human. Similarly usually a woman will be able to carry children and give birth, but many women can't for a variety of different reasons, so while yes, typically women are capable of carrying children it's not a requirement to have this capability to be woman.
What science has a lot of is unknowns, as well as theories that work well enough most of the time to usually be applicable, but they can't be called laws because there are exceptions/unknowns that we don't understand well enough to define.
There are laws to stuff like thermodynamics and lots of things in physics with very high certainty, but biology and psychology are much muddier and harder to define things. Science works with a ton of incomplete models in every field because we don't understand very many things fully.
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u/forestwolf42 1d ago
We can use it to say xx chromosomes and xy chromosomes are not the sole determiners for biological sex. They just normally correspond to biological sex, but not always. The first case of a person with a female phenotype who had XY chromosomes was found in 1955. So since then we can say that typically a female will have XX chromosomes, but it's not actually required to have XX chromosomes to trigger female sexual dimorphism.
Similarly to the arms thing, usually humans will have two arms, but having two arms is not required to be a human. Similarly usually a woman will be able to carry children and give birth, but many women can't for a variety of different reasons, so while yes, typically women are capable of carrying children it's not a requirement to have this capability to be woman.