"One of the most important strategic decisions facing veg*n advocates is whether to emphasize meat reduction or the complete elimination of meat or other animal products. Veg*n advocates’ goals are, arguably, best served by seeking out and pursuing approaches that most quickly and sustainably lower U.S. adult demand for meat products. The survey results strongly suggest a meat reduction strategy would be effective, although even with this comprehensive research, it is impossible to pinpoint any one most effective strategy. There are about three times as many people willing to reduce their meat consumption by half as those who are willing to become vegetarians. Assuming each group is equally likely to change, if there are 1,000 adults in the target audience, advocates might be able to persuade 240 of them to reduce their meat consumption by half (24% of adults are potential semi-vegetarians), but only about 70 of them to eliminate meat from their diets (7% are potential vegetarians). In this example, advocating semi-vegetarianism would yield the largest reduction in meat consumed." (emphasis added)Link: http://www.humanespot.org/system/files/HRC_Veg_Study_2007.pdf
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There are obvious methodological issues with this study, namely that people who say they're willing to do something aren't always actually willing as well as the fact that people who "eat less meat" tend to eat less meat from large animals and still consume plenty of small animals (which means that the total number of animal lives saved is less significant). However, the central idea that people are more willing to make incremental change than large sweeping change is an important concept that's worth remembering whenever performing vegan education.