The Fallacy of "Appeal to Obvious Bias"
I've noticed an informal fallacy that doesn't appear in the traditional lists in critical thinking books. I call it the "Appeal to Obvious Bias." The form of argument claims that a person with the most blatant imaginable bias would probably say that P; therefore, P. Here are some examples.
Person A claims that capital punishment is wrong. B replies, "If your child was murdered, wouldn't you want the murderer to pay with his life?"
A says that immigration restrictions are unjust. B replies, "I bet you wouldn't feel that way if your job was lost to an immigrant!"
A says that abortion should be outlawed. B says that since A is male and cannot himself get pregnant, we should disregard A's opinions.
The strategy is to first identify the most obvious emotional bias that someone could have about P, then ask your interlocutor to imagine having that bias. Then hope that your interlocutor's imagination is so vivid that the imagined bias actually takes over and changes the person's belief.
It doesn't work for all views, though. In (1), A could reply, "If you were a murderer, wouldn't you want to not be executed?" But this version of the Appeal to Obvious Bias fails rhetorically, because people refuse to empathize with murderers. The best one can do is to try, "If you were falsely convicted of a murder, wouldn't you want there to be no capital punishment?" This isn't as good as B's Appeal, because people are more inclined to empathize with murder victims' families than with crime suspects (even those falsely suspected). It makes us feel more virtuous.
Of course, all of these appeals are fallacious; there is a reason why people whose children were murdered are not allowed to sit on juries or as the judge in a murder trial.
Besides the obvious appeal to bias, part of what the Appeal to Obvious Bias is doing may be accusing the interlocutor of some moral failing -- indifference to the plight of those who are unlike oneself. In this case, the Appeal is a version of the classic argumentum ad hominem. (Of course, if you actually had failed to consider the interests of some people who are unlike yourself, then you should consider them! But usually, there is no real basis for the accusation.)
Another thing the Appeal may be doing is simply trying to make the other person feel bad for being "privileged". Then, to assuage their guilt, your interlocutor has to take up your position, presumably the position that socially aligns them with the more sympathetic, less privileged people whom you are asking them to imagine.
You might think that the person with the Obvious Bias has, in addition to an emotional bias, extra relevant knowledge that people in more fortunate positions lack. Maybe family members of murder victims have knowledge that the rest of us lack -- say, knowledge about what it's like to lose a family member to murder. True -- but how plausible is it really that that knowledge shows capital punishment to be just, in a way that can't be shown based on knowledge the rest of us already have? In most cases, it seems pretty clear that the main way the Appeal to Obvious Bias is supposed to influence us is through emotional bias, not sound inference from (imagined) knowledge.
Case 3 differs from 1 and 2 in a couple of ways. In 3, the appeal is to the perspective of a much broader group (women in general, as opposed to, say, people who lost their jobs to immigrants), and the appeal is based on the potential of this group to be in a certain position (so all women are deemed able to speak about abortion, not merely women who actually have unwanted pregnancies). Also, unlike in cases 1 and 2, in 3 the interlocutor is not asked to imagine being in that group; rather, the interlocutor is merely invited to shut up due to not being in the group with the relevant bias.
In this third case, A could respond that B is not a fetus and therefore cannot get aborted, and thus B's opinions about the issue should be disregarded.
Incidentally, the premise of the argument in 3 is factually false: women are not more in favor of abortion than men are. Women are about equally likely, or slightly more likely, to be pro-life. Which shows that women as a class do not actually succumb to the self-interested bias that B is trying to appeal to.
But those are side points. The main point is that self-interested bias, emotional bias, or other forms of obvious bias are not positive qualifications for making sound judgments.