What is the author's purpose in using antithesis in the first paragraph?

In the first paragraph of the introduction, Wollstonecraft uses antithesis to emphasize the distance between the two contradictory scenarios she presents. The example of antithesis in the first paragraph is below for easy reference:




I have had to admit, sadly, that either nature has made a great difference between man and man, or that the world is not yet anywhere near to being fully civilized.

Both of these scenarios presented by Wollstonecraft may be intentionally difficult for a reader to accept; either nature has created all men so different from one another that a search for similarities is utterly futile, or the world as it stands at the time of writing is not as sophisticated and accepting of women, who are different to men, as her readers may think it is.
By using antithesis in this way, Wollstonecraft is suggesting that the situation at hand (that of the shoddy treatment of women by men) is so appalling and so abhorrent that it can only be explained by these two difficult circumstances. It is possible that Wollstonecraft is purposefully alienating her reader in order to inspire in him or her a desire to do the opposite of what she is saying: to be more civilized and accepting of differences, as both approaches can lead to more equitable treatment of women.

An antithesis is a rhetorical device whereby two opposing ideas are put together in the same sentence to achieve a contrasting effect. Mary Wollstonecraft uses antithesis in the opening paragraph of her introduction to A Vindication of the Rights of Woman when she says that

either nature has made a great difference between man and man, or that the civilization which has hitherto taken place in the world has been very partial.

In this passage, Wollstonecraft uses antithesis to highlight one of the book's most important themes: that the most significant differences between men and women are those artificially imposed by civilization. Natural differences between men and women in terms of their respective physical strength are not the main reason why women hold such an inferior position in society. Women have been rendered "weak and wretched," argues Wollstonecraft, by means of artificial control by men. In other words, there is nothing whatsoever in women's nature which makes them fit for a life of subordination. The current lowly position of women is purely a product of society and civilization.