Today it is quite unthinkable to question the cruelty of female circumcision if you are a relatively informed person. However, to my own amazement, male circumcision (see picture) is still considered by many to be perfectly justified. It must evidently be so, considering how often this surgery is performed on young naive infants.
At one point in my life I actually became a little bit ambiguous as to whether circumcision might perhaps be justified. It was last year when, during my exchange year at UCSB, I attended some highly entertaining and informative lectures on Human Sexuality taught by two very charismatic (and married) professors John Baldwin and Janice Baldwin. You can read more about the Baldwins' view on circumcision here. I am not being ironic when I say that these were indeed great lectures, and that is perhaps why they almost convinced me that the costs and benefits associated with male circumcision more or less cancels out. As far as I can remember they referred to two positive consequences associated with male circumcision. One is the supposedly improved hygiene, which by the way is one of the most common justifications that people in favor of circumcision refers to. However, bad hygiene under the foreskin is only a problem for guys who never clean under the foreskin, so if we would simply remind guys that they need to remember to clean their more private regions this would not be a big problem. In any case I hardly think that this justifies circumcision….
The other favorable effect of male circumcision, the one that made me think that perhaps it was justified, is the reduced risk of being infected with the HIV virus. A few studies of this kind have been made and the effects superficially seem quite large. However, the studies which have shown this difference have been of poor quality, with poor control. Just as an example, in one large and frequently cited study, circumcised males were given advice on sexual behavior whereas those who had not been circumcised did not get this offer. Was the lower incidence of HIV among the circumcised due to the sexual advice or the circumcision? Studies with better control i.e. studies which try to rule out alternative explanations, have found smaller effects (see here for more information). I will not go as far as to say that circumcision does not give any improved protection at all, on the contrary, I believe that there is some truth in this. Nevertheless, it seems that the effects are significantly smaller than what the original studies suggested.
The fact that there seems to be no great benefits of circumcision is however not my main problem with it. Neither do I dislike it just because it is very much entangled with religion. I think it is a good example of how religious beliefs sometimes takes the upper hand over rational arguments, but it is not the main reason why I disprove of male circumcision. So what is the main reason? The reason is that the foreskin, which is removed during a circumcision, has a lot of very important functions. I think that this is hardly surprising because if the foreskin had been completely useless or even a burden to us, natural selection would probably have taken care of it long ago. The benefits of having a foreskin are many. To name a few, the foreskin is important because it gives protection to the glans penis, it reduces friction during intercourse, it gives important feedback to our brain about the "state" of the penis, it aids erection, and it regulates the timing of the ejaculation (people who have been circumcised often either ejaculate too early or too late). You can read about these as well as other function of the foreskin on this excellent page.
However, I think that the most important function of the foreskin, and hence also the most important reason why circumcision should not be allowed, is that it brings sexual pleasure to its owner. This of course also means that lack of foreskin will result in reduced pleasure. Sex, along with drink and food and neuroscience (that last one is probably rather personal), are things that make life worth living, and taking away the pleasure associated with sex just seems rather cruel to me. Now I am not saying that circumcised people do not feel any pleasure, I would not know, all I am saying is that there is good reason to believe that they feel less pleasure.
Summing up, besides just being a nasty and invasive surgical procedure which could well cause some kind of trauma in the infant, taking away the foreskin is associated with many other disadvantages. Even if the risk of contracting HIV would be slightly reduced, this hardly justifies circumcision.