Complex sentence: The main issue about female education relates to the traditional view of women's weakness being due to nature, then there are those like John Locke and d’Épinay who argue that women's weakness was due to faulty education.
Split into simpler sentences: The main issue about female education relates to the traditional view of women's weakness being due to nature. However, there were people, such as John Locke and d’Épinay, who argue that women's weakness was due to faulty education.