The Political Economy of Regulation of Biotechnology in Agriculture - The Oxford Topic of Food, Politics, and Society - page 666

Communist Party. In all cases, what “votes” are cast is affected by information provided
by the various competing groups; yet, this information is always weighted by the cred-
ibility of the groups in the eyes of the voters.

The Model

We assume a political system in which there are N voters indexed by if , ranging from 1 to
N. There are M interest groups, indexed by j = 1 to M. A proposition is put to a vote at time
t. Let b if t be the perceived net benefit to group j from the proposition passing at time t .
Also, assume that each voter assigns a weight for how much he or she actually cares about
the well-being of each interest group, and let W ij denote that weight given by individual if
to the net benefit of group j. For simplicity, assume that the voter aggregates the weighted
net benefits to the groups in determining his or her overall assessment of the proposition.
hus, Bj

==∗1 is the perceived net social benefit according to voter if from the
passing of the proposition. We can consider a straightforward voting system where a voter
will vote for the proposition if the net social benefit is perceived to be positive, B if t ≥ 0 , and
will vote against it otherwise. Let V if t denote the current vote of voter if at period t , desig-
nated to equal 1 when the voter is supporting the proposition and 0 otherwise. Thus,

t

Mw b

t

if ij ij

t

VifB
if

t

= 1 ≥ 0

if

t

VifB
if

= 0

t

< .

if

Now, let us assess the outcome of a voting system wherein a proposition passes
simply by obtaining a majority of votes. Let the final result of the vote be denoted by

∑ 1

N

B

t

if

, or simply the fraction of the voters who support the proposition: It

t if

R =

N

passes if the final result is greater than one-half or R t ≥ 0.5. If we rank the voters at
time t in a decreasing order of the their perceived net benefit from the proposition,
we can identify the median voter at time t as the individual if = located at the
middle of this lineup of voters.1 A sufficient mathematical condition for the propo-
sition to pass with a simple majority vote is that the net benefit perceived by that
median voter be positive, that is, B

M

∑ 1 0 . In this case, the benefits
perceived—adjusted by the weights assigned—by the median voter (or, to general-
ize, by the median group of voters) will determine the outcome of the vote.
This basic model can be used to determine outcomes in other public-choice situa-
tions. If we allow “horse trading,” such that voters are able to trade their votes with other
voters, as is the case in parliamentary systems, then voters who strongly support the
proposition may compensate others for changing their vote. If there are zero transaction
costs and voters have full information about other voters' preferences, then the system
of trading among voters will produce an outcome that will maximize the aggregate per-
ceived net benefit of all voters. Namely, the proposition will pass if aggregate perceived

t

= w b

t

> t t t

if j ij ij

m m m