Here are the main arguments against I have heard:
1) the infant has no say
, to which I say parents make decision for their children everyday. I think there is an issue, for example, with vegetarian parents denying their children meat. There is plenty of evidence (which is debatable of course) that meat is an important part of the diet. What about home schooling? This denies the child many important social skills. What about single parents (not divorcees, but women who, from the get go, decide to have children on their own by artificial insemination)? What about bringing unsuspecting kids into same sex parent households? And the list goes on....
2) The trauma causes psychological problems later on in life.
I seriously would like to meet a man who has psychological issues because of being circumcised at 8 days old.
3) It hinders one's sex life.
I haven't noticed
Nor do I know anybody who was circumcised who has.
4) It is a tradition based on "myth and superstition".
This alone is not reason to deny someone the right to carry it out. As long as one is not causing permanent harm, which countless Jews (and non-Jews) over thousand of years having gone through this procedure prove one is NOT, then if somebody wants to stand on their head for twenty minutes a day and sing lakookaratcha, that is his/her business.
5) There are cases where circumcision has caused physical harm to the infant, sometimes serious harm.
And these cases, while tragic (one is one too many) they are still very rare. Even rarer than the chance of somebody dying in a car accident DAFKA because they were wearing a seat belt (there are rare instances where a seat belt has hindered individuals from leaving the car, which would have saved their lives, but we are not going to stop wearing seat belts are we?). However, a CERTIFIED mohel is much less likely to make a mistake during circumcision than a doctor (who is not a mohel) because a mohel is trained SPECIFICALLY to carry them out. I am all for regulating circumcisions (having to have a license to perform one), but not forbidding them.