Rate of growth of veganism

I heard a statistic right at the end of this video from 2014 by vegan advocate and psychologist Melanie Joy.

In the United States, the number of vegans and vegetarians has doubled in the past three years.

This got my attention. Even with a low starting point, if that rate of increased continued, it would quickly hit 100%. How quickly? The answer might surprise you.

Estimates of the proportion of vegans within countries vary greatly from year to year, and even between studies, probably due to small or biased samples. One only needs to look at three surveys produced by the Vegetarian Resource Group in 2011, 2012 and 2015. The number of vegetarians (including vegans) goes from 5%, to 4% to 3.4%. It seems unreasonable to believe (though I wouldn’t quite fall off my chair if I’m wrong) that the proportion of vegetarians in a developed nation is dropping over recent years. The sample sizes of these studies (and many similar ones) is around a few thousand, which might give statistically significant results, but they are still uncertain. As such, I don’t believe the number is actually decreasing, and I’m happy to take a doubling of vegans over 3 years at face value for the purpose of this estimate.

If we take a lower bound and say 0.5% (which seems highly likely to be a lower bound for USA), and model in a 100% increase in proportion every 3 years, we get this.

Years from nowProportion of vegans in USA

So we might expect to see a full population of vegans, at least in USA, barring some outliers, after around 21-24 years. We assume a constant rate of growth here, which is highly unlikely to be true. But will it get faster or slower over time? When we look at many social justice movements (e.g. black rights, abolition of slavery), they follow an exponential growth rate [do they?]. We might also expect veganism to hit a run away critical mass. We should probably also expect that there will be some people who will simply take much longer to change their underlying beliefs if not their actions, just like we still have some people who wish minority groups are still treated differently in secret. In the same way, animal exploitation will probably be illegal long before all humans disagree with it. If we’re off on the growth rate by double, as in it is only doubling every 6 years, we’d still simplistically expect to see a vegan USA within 48 years.

This is incredibly simplistic and possibly over optimistic, but it does serve to bring some hope. We might be closer to the end of exploitation than we think. We’re winning the fight, but we can’t let up.

The Vegetarian Resource Group studies for 2011, 2012 and 2015.

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