Meat eaters who justify their eating habits feel less guilty and are more tolerant of social inequality, say a group of authors led by psychologist Dr. Jared Piazza of Lancaster University.

Omnivores also rationalize, say the team. They have labeled the most common justifications for not adapting a vegetarian lifestyle as "the 4Ns - that meat consumption is Natural, Normal Necessary and Nice.

Natural - “Humans are natural carnivores”
Necessary - “Meat provides essential nutrients”
Normal  - “I was raised eating meat”
Nice - “It’s delicious”

The group asked students and adults in the United States why they find it okay to eat meat, which is inappropriate framing from the outset. The largest category used to justify their choice was that that it is “necessary” followed by the other three categories. The authors believe that the rationalizations are probably invoked because morally-motivated vegetarians are a source of implicit moral reproach for normal human diets, eliciting rationalizations designed to defend against moral condemnation. When it comes to moral condemnation, it is true that meat eaters are far more tolerant than vegans.

Yes, she rationalizes eating meat, but at least she is not intolerant, but she is more tolerant of social inequality but she is still cooler than Pescatarians and Fruitarians. Source: Demotivational Posters

But that is not the worst of it. The group also found that people who rationalized using one of the 4 Ns were more likely to be tolerant of social inequality.  

 “The relationships people have with animals are complicated. While most people enjoy the company of animals and billions of dollars are spent each year on pet care and maintenance, most people continue to eat animals as food. People employ a number of strategies to overcome this apparent contradiction in attitude and behavior," says Piazza. “The 4Ns are a powerful pervasive tool employed by individuals to diffuse the guilt one might otherwise experience when consuming animal products.”

Citation: Jared Piazza, Matthew Rub, Juliana Kulik Steve Loughnan, Mischel Luong, Hanne Watkins, Mirra Seigerman 'Rationalising Meat Consumption. The 4Ns', Appetite' 
http://www.sciencedirect.com/science/article/pii/S0195666315001518