1. Mention of the television show "24." Try to find an anti-torture argument on the internet that doesn't mention this show. This is a non-argument to anyone who hasn't watched 24. And for those who have, it rests on the illogical premise that something which happens in fiction can't possibly occur in real life.
2. Mischaracterizing people as pro-torture, when they are not. Many people, probably a majority, who advocate waterboarding and other enhanced interrogation techniques, do not believe that such methods constitute torture. Torture is obviously difficult to define, and subject to opinion. Pretending that one's assumptions equal fact, and ignoring that others have different underlying assumptions, is typical of many bad arguments. [Note: I do consider waterboarding to be a mild form of torture. But I recognize that opinions differ and that my personal opinion on this issue is not a fact.]
3. Pretending that utility arguments have to be unrestricted in scope. This is the common, if you are willing to torture terrorists, why aren't you willing to torture their children, line of argument. It's an apples & oranges situation that ignores the fact that utility arguments can be restricted to defined categories. Making a utility argument with regard to the treatment of terrorists does not imply that you must extend that utility argument to a different category of person. Categories matter.
4. The seeming inability to distinguish a moral difference between actions taken against the guilty, and the same actions taken against an innocent. This usually goes along with bad argument #3.
5. The assumption that torture is itself inherently immoral. It is quite possible to believe and argue that torture is inherently neutral, and the morality of its use depends on the circumstances. Many of the same people who normally have no problem with moral relativism in other cases, assume that a strict moral absolutist position on torture is the only rational position. It isn't.
6. Torture is a recruiting tool for our enemies. You know what else is a recruiting tool for our enemies? Our existence. Without some sort of reasonable quantification, this argument is completely meaningless. In addition, it ignores the fact that many terrorist recruits believe all sorts of fantastic nonsense about the U.S. and the world at large. Their beliefs and anti-Americanism have little to do with carefully analyzing our actions and making a decision as to whether or not they want to become a terrorist.
7. Torture undermines the "rule of law." The use of this phrase is almost always a red-flag that a bad argument is in progress, since the term has become virtually meaningless. If the law is interpreted to allow torture under certain circumstances, then torture is itself under the rule of law.
8. An inability to recognize the difference between U.S. citizens and non-citizens, or that there is major disagreement over the concept of rights. This is similar to bad arguments #2 & 5, substituting personal assumptions for fact. Many people, probably a majority in the U.S., do not believe that non-citizens, particularly hostile alien terrorists, have, or should have equivalent rights to U.S. citizens. If someone is arguing that non-citizens might be subjected to torture because they lack rights, arguing that torture violates their rights, based on your own expansive definition of rights, is not too convincing.
9. Torture is un-American. This is not only a meaningless argument, but also demonstrates historical ignorance. Given the loose definition of torture preferred by many anti-torture types, it also reflects ignorance of how some civilian criminals are treated in our own prison system.
10. Torture doesn't work. Anyone with five minutes and access to Google can find concrete examples of torture working to extract accurate information. Throughout history, countless thousands have been tortured in order to force them to reveal the hiding place of their valuables. This was a common pastime for marauding armies in hostile territory. The people who were robbed in this way would be amazed to learn that there are actually people stupid enough to believe that torture can't work to obtain accurate information. Obviously torture can and does sometime work, depending on the information in question, the torturer, and the victim. Pretending that torture doesn't work is not only a completely illogical dismissal of everything we know about human nature and motivations, it is also an outright denial of reality.
Coming tomorrow -- the Top 10 Good Arguments Against Torture.