Well there's a potential minefield for ya. I'm not sure why I would hazard to even try and write about this -- as a man, me telling women "ur doin it rong" in regards to feminism is unsavory at best, almost always condescending, and just generally a bad idea. But I have some thoughts about it, and I'd like to take my mind off some other stuff, so I thought I'd share what I have to say.
My thesis here is that the most sensible "feminist" position on the issue would be that a) women should be maximally facilitated to breastfeed if they choose to do so, including legal protections on doing so in public and employers providing a place to pump; while b) women should not be unduly pressured to breastfeed if they don't want to, that they especially should not be made to feel like they have failed or anything like that, and that if somebody's reason not to is simply "I just don't want to", that should be accepted uncritically. I will now try and defend that position.
It is important when we discuss anything like this to be ever mindful of the naturalistic fallacy. Nature has given women a distinctly different deal than it has given men in regards to this issue, and we should not be confused into thinking that this implies anything about what ought to be the case. At the risk of pissing off so-called lactivists -- whom I largely agree with, by the way -- the fact that breastfeeding is natural doesn't inherently argue that women ought to do it, nor does it even in and of itself mean that it ought to be socially acceptable to do so in public. There are plenty of things that are "natural" that we don't tolerate in public, sometimes with very good reason. I happen to feel very strongly that public breastfeeding ought to be tolerated and even encouraged, but my reasoning has very little to do with it being "natural".
So shall I proceed to those reasons? For starters, there really isn't any defensible reason not to tolerate public breastfeeding. There's nothing other than social convention that makes some people find it unseemly. Nature enters into it a little here in that if people did naturally find it disturbing, then we might want it to be a private activity; but it's not like that and I really just can't see any argument not to tolerate it.
More importantly, however, a lack of tolerance for public breastfeeding adds an additional burden to those who might choose to breastfeed. Constantly being shunted off to a bathroom or some other private location interferes with a breastfeeding woman's ability to fully participate as an adult in social and professional situations. Nature has already dictated for us that if a child is to be breastfed, it is the mother who will be doing the bulk of the work; there's no reason we should exacerbate this imbalance.
There's an important caveat here, that if a woman is not herself comfortable with breastfeeding in public, that is her business and nobody should be criticizing that. I guess some people even feel that it is a betrayal of values for a woman to cover when she is breastfeeding in public! No way. Even if it is an unfair social convention that creates this lack of comfort, a woman should not be forced to be a martyr for social change if she wishes to breastfeed.
I think this is so important that I favor legislation clarifying that any place which allows infants must also allow breastfeeding, and legislation forcing employers to provide for mothers to pump during the workday.
I don't want to make it sound here like I am characterizing breastfeeding as an inherently unpleasant or burdensome activity -- far from it, many women find it very rewarding and enjoyable. In fact, biology has also been unfair to men here, in telling us that we can't breastfeed even if we want to. (I guess it can be done with hormones and such, and certainly feeding an infant from a bottle provides some of that same feeling of bonding... but the point is that even if we have overcome nature in this regards, which I'm not convinced of, our natural biology was still unfair) I do not want it to come across as if I am saying, "Nature has shafted women by making them breastfeed, and we should undo the damage as much as possible." Rather, I am saying that our biology creates an inequity, and that inequity should be minimized without regard to whether it is inherently positive or negative.
So what about the flipside? Can advocacy in favor of breastfeeding become an anti-feminist position? Again at the risk of being patronizing, I think it can if we are not careful.
As already mentioned, even in the best of situations nature has dictated to us that if a child is to be breastfed, the mother will be doing most of the work to facilitate that. (Even if the mother were to exclusively pump and her partner or other family members did all the feeding, it still can be a physically and emotionally demanding activity, and in any case some women simply may not feel comfortable with it) By providing an alternative to breastfeeding, formula potentially frees mothers from this obligation. You can now be a mother and not breastfeed if you don't want to. When we denigrate that, we are aiding and abetting an unfortunate misogynist aspect of our biology.
Another important digression on the naturalistic fallacy is due here. The preponderance of evidence does seem to show that breastfeeding is superior to formula feeding -- but we can only have determined that by evidence, not by reasoning it out or favoring what is "natural". There are plenty of examples where "unnatural" things are clearly superior. Just thinking in the category of "things that are consumed", fortified milk, iodized salt, and fluoridated water are all relatively uncontroversial examples. (Apart from the anti-fluoridation crackpot conspiracy theorists, there are some legitimate questions about the cost/benefit of the amount of fluoridation that is employed in some areas, but there's little doubt that the practice itself has been beneficial) So it could have been the case that formula turned out to be much healthier than breastfeeding for some reason. It's not, but we couldn't have known that without evidence.
And furthermore, it's important not to oversell the benefit. While the data is mixed, the benefit does appear to be fairly modest. It's not like using formula is automatically going to make your child fat, stupid, and emotionally maladjusted. It may very slightly increase the odds that she will be obese as an adult, to pick one example of a possible benefit to breastfeeding -- but we all make choices every day that affect our children's future, sometimes negatively, and unless it's something with a really pronounced effect, e.g. like smoking during pregnancy, there ought not to be a moral stigma attached to it.
Telling a woman that she is failing her child if she doesn't breastfeed is equivalent to saying that you should not be allowed to be a mother unless you are willing to conform to your "proper" womanly role. And that is a distinctly anti-feminist thing to do. In my male opinion, that is.
Biology has not given men and women equal treatment; we cannot change this. But as I have argued previously, that doesn't mean gender inequality is a good thing! If we value gender equality -- and I do, very much so -- then we ought to do whatever we can to minimize the impact of those facts of biology which get in the way. In the case of breastfeeding, that means doing everything we can to facilitate women who choose to breastfeed, and it also means letting women know it is perfectly alright to make a choice not to breastfeed. Ultimately it's about empowering the individual to be whatever he or she wants to be -- nature be damned.