Animal Rights: The Abolitionist Approachach wrote:A single-issue campaign involves identifying some particular use of animals or some form of treatment and making that the object of a campaign to end the use or modify the treatment. The problem of a single-issue campaign is that it presents some particular use or treatment as morally distinguishable from other forms of use or treatment and by doing so explicitly or implicitly suggests that other forms of exploitation are morally less problematic.
Blog entry by Gary Francione about single-issue campaigns. Is Every Campaign a Single-Issue Campaign?
As for veganism being a single issue campaign. Clearly it is not
Animal Rights: The Abolitionist Approachach wrote:..when I talk about veganism, I talk about not eating, wearing, or using any animal or animal-derived product for any human purpose. But even if you restrict your understanding of veganism to “a vegan diet,” you are still advocating the elimination of a practice that involves more animals than all of the other animal uses combined because everyone who is not a vegan consumes animals and animal products.

