Discuss the wiki-tag on this page. Here is the place to ask questions and propose changes.
The Knobe effect may give some support to Simler and Hanson's speculation. It says that while bad side-effects are assumed to have been brought about intentionally, good side-effects are assumed to have been brought about unintentionally. Marginal charity may be perceived as (good) side-effects, and as such unintentional.
As discussed in the "ethics of personal consumption" entry, some have suggested that we should divide our resources into a "budget for ourselves" and a "budget for others". At least on one interpretation, that is in some tension with the notion of marginal charity - which says that you can sometimes have an outsize impact by shifting your selfishly motivated actions (part of the "budget for yourself") in a prosocial direction. Marginal charity-considerations suggest that we should be alert to altruistic opportunities even when using the resources that we've budgeted for ourselves. Potentially this should be briefly pointed out.
Thanks, this is an interesting point.
Hanson describes marginal charity in a way that suggests altruistic agents should consider making slight changes in a prosocial direction for each of the countless choices they face in their lives. So, in deciding what to eat, you may want to order slightly less meat to slightly reduce animal suffering; in deciding how much to tip, you may want to tip slightly more to slightly benefit the waiter; in deciding how to leave the restaurant, you may want to walk slightly more before calling an Uber, to slightly reduce your carbon footprint. But these "local" prosocial moves are obviously inefficient: e.g. the money you "donate" to the waiter could instead provide months of seasonal malaria chemoprevention to a family in Burkina Faso. The rational approach is to consider all your choices simultaneously and introduce deviations in a prosocial direction as part of a global choice portfolio. But revised in this way, marginal charity begins to look very similar to budgeting.
[Added: I no longer endorse the last sentence in the previous paragraph, and don't think the comment addresses the point Stefan was raising.]
Right. Here's one way to think about it. There's a simple model according to which you divide your resources into two buckets:
a) X resources that you use for yourself. You can use them however you like (though presumably only as long as you don't harm others, follow laws, etc). You don't consider the interests of others when you're using these resources.
b) 1-X resources that you use for your others.
You're not considering your own interests when you're using these resources.
But I take it that Hanson is saying that sometimes when you're using resources for yourself, there are opportunities to help others greatly at relatively small cost for yourself. If you take those opportunities, then your actions effectively have mixed motives - they are partly selfishly motivated, and partly altruistically motivated.(Note that the converse also holds - sometimes when you're helping others, you have opportunities to substantially benefit yourself at a small altruistic cost.)
You could create a more advanced version of the "budgeting for yourself and for others" model, where each action is classified on a continuum from 0% selfish/100% altruistic to 100% selfish/0% altruistic. So if an action that costs Y resources is 70% selfish and 30% altruistic, you've used up .7Y of the selfish resources and .3Y of the altruistic resources. The total amount that you budget for yourself could remain at X - the only thing that has changed is that you can use specific resources in a hybrid way.
It seems tricky to put percentages on these hybrid actions, however. The simple model is much more straightforward, which is indeed an advantage.
When you divide your resources into self-regarding and other-regarding buckets, you are trying to balance your egoistic and altruistic concerns optimally. So it looks like if you then apply marginal charity to your self-regarding bucket, you'd be moving away from the all-things-considered optimum, biasing your choice in an altruistic direction.