One interesting impact of deliberation is that it can induce single-peakedness which makes the problem of social choice easier. Briefly:
There are a number of social choice impossibility theorems (e.g. Arrow, Gibbard-Satterthwaite) which say that, in general, it’s impossible to aggregate individual preferences into social choices/preferences without giving up on some criterion you’d really like to satisfy (e.g. no dictators; if every individual prefers A to B, so does society).
every participant views options as varying along a single dimension,
every participant has an ideal choice in the set of choices, and
options further away from that ideal choice are less preferred.
If you restrict the domain of input, individual preferences to be single-peaked, you can escape some of the impossibility theorems and straightforward aggregation options become available.
It’s plausible that deliberation causes a single dimension to become salient for everyone and for preferences to thereby become single-peaked.
I believe this point on social theory was discussed during Mahendra Prasad talk at 2019’s EA Global London (I didn’t attend it but Mahendra sent me the slides). This hypothesis that deliberation could shift individual preferences toward single-peakedness appears to be lent support in deliberative poll experiments (e.g. Farrar et al. 2010). I did not see a neat way to explain this point in the essay, but have included a small mention of it instead. Thanks for offering this useful summary!
One interesting impact of deliberation is that it can induce single-peakedness which makes the problem of social choice easier. Briefly:
There are a number of social choice impossibility theorems (e.g. Arrow, Gibbard-Satterthwaite) which say that, in general, it’s impossible to aggregate individual preferences into social choices/preferences without giving up on some criterion you’d really like to satisfy (e.g. no dictators; if every individual prefers A to B, so does society).
Single-peaked preferences are preferences where:
every participant views options as varying along a single dimension,
every participant has an ideal choice in the set of choices, and
options further away from that ideal choice are less preferred.
If you restrict the domain of input, individual preferences to be single-peaked, you can escape some of the impossibility theorems and straightforward aggregation options become available.
It’s plausible that deliberation causes a single dimension to become salient for everyone and for preferences to thereby become single-peaked.
Social Choice Theory and Deliberative Democracy: A Reconciliation talks about this kind of thing in more detail.
I believe this point on social theory was discussed during Mahendra Prasad talk at 2019’s EA Global London (I didn’t attend it but Mahendra sent me the slides). This hypothesis that deliberation could shift individual preferences toward single-peakedness appears to be lent support in deliberative poll experiments (e.g. Farrar et al. 2010). I did not see a neat way to explain this point in the essay, but have included a small mention of it instead. Thanks for offering this useful summary!