ECONOMY

192 bicameralism
5 Informational Explanations
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Another potential argument for bicameralism is that it may promote more informed
legislative decision-making. Since passage is required by multiple chambers, a “twoheads
are better than one” logic suggests that bicameralism should lead to better
legislative decisions. Rogers (2001) attempts to formalize this logic to provide an
informational rationale for bicameralism. In his model, the reconciliation of interchamber
differences through a “conference” committee allows for the aggregation
of information that is dispersed across chambers. 18 Since it allows the dispersed
information to be aggregated, a bicameral process is less likely to produce the wrong
decision than a unicameral process. In fact, information is better aggregated when
the chambers have congruent preferences. Thus, Rogers presents his model as an
argument for congruent bicameralism.
While suggestive, Rogers’s model is restrictive, and it is unclear how well it would
generalize. Each chamber is modeled as a unitary actor with an exogenously given
level of information about the desirability of its policy choices. It is not clear why
the dispersal of information across chambers should be so much greater than within
chambers. Indeed, it is not clear why consolidating the two chambers into a single
unicameral chamber does not aggregate information at least as well as the bicameral
procedures.
A more general analysis of the role of bicameralism in aggregating information
can be grounded in models of voting under incomplete information and common
values—the so-called “Condorcet jury problem.” These models seem to suggest a
much more circumscribed informational benefit of bicameralism.
Consider n legislators who must decide whether to choose policy 0 or policy 1.
They all have a common preference for choosing the correct policy. They each get
an independent signal about which policy is the common preference. We assume
that each player’s signal is correct with probability apple. 19 This model predicts that the
probability of making a correct decision under majority rule is an increasing function
of both committee size n and signal quality apple.
We can compare these results to bicameralism by dividing the n legislators into two
chambers. We assume that each chamber votes via majority rule. Now the probability
of making a correct decision depends on which policy is enacted when the chambers
disagree. However, if the disagreement policy turns out to be incorrect, bicameralism
would perform far worse due to the requirement that both chambers reach the correct
decision. Thus, the probability of a bicameral correct decision is much lower than that
for unicameralism since each chamber is smaller and thus more likely to produce the
¹⁸ A conference committee composed of members appointed from each chamber to negotiate
inter-chamber differences is a common way of ensuring that bills pass each chamber in an identical
form. Typically, a conference committee produces a final bill or report which is voted up or down in each
chamber.
¹⁹ Allowing the signal quality to vary across individuals is unlikely to change our analysis so long as
signal quality does not vary systematically across chambers in the bicameral case.