Sure, I didn’t discuss the connection between your demand decrease and the remaining people’s elasticities. Let’s use Brian’s example of the supermarket supply system to illustrate that connection.When you stop buying chicken, demand in the store has decreased. Perhaps it decreases to the point where the store decides to put the chicken on sale. Other shoppers who still buy meat will see the sale price and change their purchases according to their price elasicities, which are defined as the percent change in quantity demanded given a 1% change in price. Using the specific example of the paper’s elasticity, a 1% decrease in price would cause a shopper to buy 0.68% more chicken. In the next ordering cycle, the inventory manager orders less chicken because you decided not to buy chicken and because the other shoppers purchased some of the excess stock at the sale price. We could call this a new equilibrium, and we see that equilibrium quantity demand has shifted. I won’t make an assumption on whether the equilibrium price is lower in this little supermarket scenario (only because I’m not sure how supermarkets actually set their prices).These causal pathways are always a little tricky because you can always talk your way out of any scenario, but the underlying mechanism behind a demand shift in a larger, more abstract market could work like this.This hypothetical supermarket brings up your second point. You’re right for calling me out on my statement about not making a difference—your non-purchase of meat in a grocery store does have the probability of setting off a chain reaction in the supply chain that reduces the number of chickens killed in expectation. I should have been more clear in my previous comment, because I was certainly thinking of a larger-scale aggregate market like, for example, the entire US market for chicken. In this case, you are one of ~300m people in the market for chicken, and your one-time non-purchase would have a small effect that would be hard to estimate (this is a more precise statement of what I meant).I do believe that you save may chickens, in expectation, with a non-purchase. And further, I do believe that your continued non-purchase of chicken and your entry into the alternatives market will, in expectation, save more chickens. I also believe that your non-purchase of chicken will likely lead you to change other purchasing decisions according to your ethics, and I believe that your ethical decisions will, in expectation, influence the people around you. (This is also something I’d like to study formally in the future.) So I believe, in expectation, you can do a lot of good!