The relevance of the ideal world is vastly overrated. 

More specifically, although a lot has been learned in the last few decades about how legislatures work, much of what researchers hold to be true is riddled with impossibilities or tradeoffs. In effect, positive social scientists have uncovered several counterparts to the conflicting principles represented in Alan Rosenthal's essay. As an illustration, consider one of several recent theories of legislative choice. In Information and Legislative Organization, I summarized a rational choice theory that Tom Gilligan and I developed in the late 1980s and presented several forms of evidence consistent with the theory. In a nutshell, the theory postulates that legislatures are majoritarian organizations, both with regard to policy choice and procedural choice, and that legislators are uncertain about the consequences of many policies about which they and their constituents care. The theory predicts that rational legislators will make organizational choices that balance two factors: the desire of all legislators to make informed choices about the effects of policies, and the desire of moderate legislators (technically the median voter) to choose outcomes that are congruent with, representative of, their preferences. In subsequent work, Gilligan has extended the theory to one in which legislators also care about the speed or responsiveness at which collective decisions are made. 

The good news is that this class of positive theory can make definitive analytical statements about three normative criteria--informativeness, representativeness, and responsive-ness--that subsume a large fraction of Alan Rosenthal's list. The better news is that these theories, while admittedly abstract, nevertheless have received a modest to large amount of empirical support over the past decade or so. There is no best news, however, because if pressed on the question of whether this evidence is sufficiently clear-cut to translate the positive theory into normative prescriptions, I cannot answer "yes" with high confidence. There are two reasons. 

First, although the best positive theories have well-defined concepts and are analytically rigorous, their well-defined concepts (e.g., preferences) are notoriously difficult to measure. Consequently, most of what we know about the consequences of legislatures and legislative reforms is based on somewhat crude empirical tests. As a practical matter, it is almost impossible to defend one or another change in the legislative system if one has, at best, only a rough idea about how to generate good consequences. Still, it is helpful to get a sense of what is possible, and here (and perhaps here, uniquely) some positive theories offer some insights. Specifically, the informational theory's overall assessment of how informative, representative, and responsive a legislature can hope to be is a gloomy one due to a seemingly inherent tension between the three criteria. For instance, if legislators value policy information or expertise, they can provide incentives for legislative committee members to specialize by enlarging their staffs or by protecting their bills from amendments on the floor--but not without a cost. Restrictive rules also increase the likelihood that the committee will propose a policy that moderates on the floor prefer to no bill at all, but just barely. Thus gains in information tend to correspond with losses in representativeness. Similarly, supermajority procedures are conducive to the deliberative role of the legislature which in turn helps to inform policy choices. Like it or not, this is why the Senate's filibuster is sometimes euphemistically called "extended debate in the world's most deliberative body." The dark face of deliberation, however, is gridlock, and gridlock is just a stone's throw from the absence of responsiveness if the majority but not the supermajority threshold can be crossed. 

Second, a deeper problem occurs in the unlikely event that an ivory tower consensus emerges on how to trade off principles that are, to the best of our knowledge, inherently conflicting. The brutal fact under most constitutions is that legislators themselves ultimately "determine the rules of [their] proceedings" (e.g., Article 1 section 5 of the U.S. Constitution). Even if legislators were to share our conceptions of the good legislature, they face incentives in the rough and tumble world of real politics that mitigate against bringing such a legislature into existence. The logic of it all is really quite fiendish. Suppose my premise were false, i.e., that legislators are not motivated more by instrumental politics than our (hypothetical) view of the good legislature, in which case the problem is obvious. Normative prescriptions would be based on a manifestly bad positive model. 

So is the prospect of solid normative analysis of a good legislature hopeless? Not quite, but it is necessarily premature if, as I suspect and have assumed, most of us are consequentialists at heart.²The bottom line is that good practical normative analysis of legislative systems is being held hostage by the absence of widely accepted positive analyses of legislative systems. Until we positivists do our jobs better, the cold truth is that thoughtful scholars and practitioners of a normative bent confront a dilemma: either they abdicate by declining to make prescriptions, or they build prescriptions on a necessarily shaky foundation. That's not the way it ought to be, but that's the way it is. 

Notes

1. The organizer of the May meeting in Washington affirmed that this was my role. 

2. The other normative game in town--so-called deontological systems--are conducive to deriving some bare-necessity requirements of good legislatures. Kant, for example, employs criteria of universalizability and reversibility to derive the categorical imperative (which bears a striking resemblance to the Golden Rule in the Bible). Some might construe "do unto others. . ." as a prescription for the norm or reciprocity, a.k.a., logrolling writ large. A less cynical interpretation I share is that parliamentary rights be allocated uniformly to legislators. Attempts to apply this theory in my experience as a sometimes professor of business ethics typically produce a mix of fireworks, frustrations, and an at hoc retreat to utilitarianism as a tie breaker.

References

Gilligan, Thomas W. 1991. "Performance of an Institutionalized Legislature." Political Analysis3: 1-25. 

Krehbiel, Keith. 1991. Information and Legislative Organization. Ann Arbor: University of Michigan Press.