p22.
Stephen Toulmin, Richard D. Rieke and Allan Janik (1984), An Introduction to Reasoning, pp 147–148. Toulmin et al. (1984) are writing here about compassion, but it is “pity” (Argumentum ad misericordiam) that is generally discussed in the logic literature. See, for example, Charles Leonard Hamblin (1970), Fallacies, p 43.