The vegan ideal refers to veganism, obviously. The distinction between theoria and praxis - between the ideal / teachings / theory and how followers choose to implement it in their daily lives - is one that is common and widely accepted in other philosophies, ideologies and belief systems, e.g. Christianity. The theory is more strict (the 10 Commandments etc.), whereas the practice / implementation is often not perfect. The followers, e.g. Christians, are often accepted as such despite their departures from the theory, though sometimes they go too far. Exactly where that line is in the case of veganism is difficult to articulate, and obviously opinions vary ...