The effect of this development is to make veganism unique among movements concerned with animal welfare. For it has crystallised as a whole and not, as are all other such movements, as an abstraction. Where every other movement deals with a segment – and therefore deals directly with practices rather than with principles – veganism is itself a principle, from which certain practices logically flow.
If, for example, the vegan principle is applied to diet, it can at once be seen why it must be vegetarian in the strictest sense and why it cannot contain any foods derived from animals. One may become a vegetarian for a variety of reasons – humanitarian, health, or mere preference for such a diet; The principle is a matter of personal feeling, and varies accordingly. Veganism, however, is a principle – that [humans have] no right to exploit creatures for [our] own ends – and no variation occurs.
In his three books, Animals, Property, and the Law, Rain without Thunder: The Ideology of the Animal Rights Movement, and Introduction to Animal Rights: Your Child Or the Dog?, Gary L. Francione lays out his theory of nonhuman animal rights. However, none of these books discuss veganism as a principle itself. Of these three book veganism is only mentioned once; relegating veganism to a footnote in Rain without Thunder, Francione simply stating: "Veganism is a diet that excludes all animal products, including eggs and dairy products."
Yet, in his most recent book, Animals as Persons: Essays on the Abolition of Animal Exploitation, Francione does discuss veganism. In the "Introduction," he states:
On the individual level, the rights position prescribes incremental change in the form of veganism. Veganism means not eating meat, dairy, eggs, honey, and other animal products, or wearing or using animal products or products tested on animals. Veganism, which results in a decreased demand for animal products, is much more than a matter of diet, lifestyle, or consumer choice; it is a personal commitment to nonviolence and the abolition of exploitation.
Veganism is discussed at greater length in the chapter, "Reflections on Animals, Property, and the Law and Rain without Thunder," where Francione states that veganism "is a moral and political commitment to abolition on the individual level and extends not only to matters of food, but to clothing and other products."
So while in Rain without Thunder he wrote that veganism is "a diet," in his latest book Francione writes that veganism "is much more than a matter of diet" and that it "extends ... to clothing and other products." However, this is only a minor improvement, since Francione is still treating veganism as an individualized, (non)consumptive practice, which marginalizes veganism. That is, simply extending veganism from "a diet" (Rain without Thunder) to include "clothing and other products" (Animals as Persons) does not adequately describe veganism as a philosophy and way of life. As Leslie Cross made clear in "Veganism Defined," "veganism is itself a principle, from which certain practices logically flow" (emphasis in original). Instead of acknowledging that certain practices are what logically flows from the principle of veganism, Francione states that veganism means practice and replaces veganism as the reason for these practices with what he calls "the rights position."
Now this doesn't mean that veganism and the rights position cannot both logically lead to "not eating meat, dairy, eggs, honey, and other animal products, or wearing or using animal products or products tested on animals." In Rain without Thunder, and without the need to appropriate "veganism," Francione writes, "if animal rights means anything, it means that as a society and as individuals we can no longer countenance the institutionalized killing of animals for food, any more than we can justify performing experiments ourselves, or wearing clothing made from animal skins or pelts."
But as Cross said, "One may become a vegetarian for a variety of reasons," and this is also true when not using other animals extends to clothing and other products. However, the principles themselves, that is the reasons for not using other animals, are fundamentally different depending on whether we're discussing veganism or the rights position. Stated briefly, veganism is based on liberation and the vegan ideal of avoiding exploitation, and Francione's rights position is based on equality and the humane-treatment principle of avoiding unnecessary suffering. As I'll discuss at greater length in a future post, this contributes to two significantly different frameworks for nonhuman animal advocacy.

