Can inconsistency in legislators’ voting records be explained by the uncertainty they have
about their constituency? Why does a two-dimensional model of roll-call voting explain the
votes of some legislators better than others? In this paper, we present an uncertainty-based
theory of legislative voting and inconsistency. We test this theory by examining whether U.S.
senators’ uncertainty about their constituency leads to higher levels of inconsistent voting in
Congress. Specifically we compare southern senators who faced a large influx of black voters in
the 1960s and 1970s with southern senators from more stable constituencies. We also examine
other factors that can cause legislator uncertainty, such as legislators’ backgrounds.
The impact of increased black enfranchisement on the politics of the U.S. South and
nation has been noted by many (e.g., Alt 1994; Black and Black 1987; Davidson and Grofman
1994; Keech 1981; Matthews and Prothro 1966; Stanley 1987). We also know quite a bit about
ideological shifts among southern House members in response to black enfranchisement and
increases in black voting power (Black 1978; Bullock 1981; Combs, Hibbing, and Welch 1984;
Feagin 1972; Fleisher 1993; Hood and Morris 1998; Rae 1994; Rohde 1989; Whitby 1985, 1987;
Whitby and Gilliam 1991). Much less is known about senators’ roll-call voting (though see
Hood, Kidd, and Morris 1999; 2001; Hutchings, McClerking, and Charles 2004), and we know
very little about the factors that explain variation in the consistency of voting records in
Congress. Why do some legislators vote in highly unpredictable patterns—voting with
conservatives on some issues and with liberals on others? At first blush, an inconsistent voting
record may appear to be odd at best and irrational at worst. Fenno (1996, 277) declares that a
“[l]ack of consistency…feeds the media’s appetite for inconsistency, generates dissonance
between free media and paid media, and in general opens possibilities for political attack or self-
destruction.” Given these risks, why would any legislator vote inconsistently?
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Convention