Sorry for the long quote, but please advise how I should abridge it; feel free to emend this post.
Source: p 127, A Concise Introduction to Logic (12 Ed, 2014) by Patrick J. Hurley
The appeal to pity fallacy occurs when an arguer attempts to support a conclusion by merely evoking pity from the reader or listener. This pity may be directed toward the arguer or toward some third party. Example:
[1.] Taxpayer to judge: Your Honor, I admit that I declared thirteen children as dependents on my tax return, even though I have only two. But if you find me guilty of tax evasion, my reputation will be ruined. I’ll probably lose my job, my poor wife will not be able to have the operation that she desperately needs, and my kids will starve. Surely I am not guilty. [End of 1]
The conclusion of this argument is “Surely I am not guilty.” Obviously, the conclusion is not logically relevant to the arguer’s set of pathetic circumstances, although it is psychologically relevant. If the arguer succeeds in evoking pity from the listener or reader, the latter is likely to exercise his or her desire to help the arguer by accepting the argument. In this way the reader or listener may be fooled into accepting a conclusion that is not supported by any evidence. The appeal to pity is quite common and is often used by students on their instructors at exam time and by lawyers on behalf of their clients before judges and juries.
Of course, some arguments that attempt to evoke sympathetic feelings from the reader or listener are not fallacious. We might call them arguments from compassion. Such arguments differ from the fallacious appeal to pity in that, in addition to evoking compassion on behalf of some person, they [2.] supply information about why that person is genuinely deserving of help or special consideration. [End of 2.]
Whenever possible these nonfallacious arguments should show that the person in question is a victim of circumstances and not responsible for the dire straits he finds himself in, that the recommended help or special consideration is not illegal or inappropriate, and that it will genuinely help the person in question. In contrast to such arguments, the appeal to pity proceeds by ignoring all of these considerations and attempts to support a conclusion by merely evoking pity from the reader or listener.
How is an Appeal to Pity (which can satisfy 2) not an Argument from Compassion?
Suppose in 1 that the culpable taxpayer is being honest. Then he is not trying only to evoke pity from the judge, because he does explain why he had to evade taxes and so 2 appears satisfied. So how is 1 above NOT an Argument from Compassion?