If a person is both vegan and anti abortion, which do you hear first ? So goes the joke...
The main reason I know for abstaining from meat or animal derived products is harm reduction. This is based on utilitarianism. The view that the pain and suffering the animal goes through from inception to slaughter outweighs the pleasure we derive from consuming it. This conclusion is a bit more intuitive if we factor in the amount of meat we consume as well as how much of it is thrown away or misused. But then, all this is a question of degrees. It doesn't have to be an all or nothing thing.
I am all for feeling gulity of consuming meat when I could have chosen a nutritionally equivalent plant-based meal. I doubt this position is original, but it nonetheless deserves some thought. For example, in arctic climates, agriculture is impossible, so meat is the only source of nutrition. I can hardly see someone seriously propose veganism to people living like Inuits (used to, or maybe still do). The same for people raising their own pigs and chicken then consuming them once a year. The only time a year they actually do consume meat. It's not unheard of to both enjoy the meat and feel sad at the loss of the animal you hand fed.
Edge cases apart, I also have no beef with occasional consumption of meat, even in modern societies.
On the "harm spectrum", we have bio and/or organic food. This is not bullshit. For meat products to qualify as organic, there are measurable standards to be enforced. It can be argued that organic grown animals suffer less than non organic ones.
Then there is the plain distinction between animal products and animal meat. I feel less remorse when eating organic products compared to organic meat. The following are all things to factor in when choosing your next meal.
- Animal products vs meat.
- Organic vs non organic
- Occasional vs regular consumption
- Amount thrown away.
At one end, you have the regular double triple extra meat burger consumer, most of it he throws away, versus the occasional organic egg buyer. None qualify as vegan, but one is much more reasonable than the other.
Far from being an absolutist annoying concept, meat and animal products consumption should be thought of a bit more, in my humble opinion.