A couple of comments, if i may

1. I detect a fundamental misunderstanding of rational choice theory. I am not sure whether I can clarify things but am going to give it a shot.

Rational choice theory is a analytical device, or a perspective, or an epistemology. It is a "theory" in terms of game theory, principal-agency theory, social choice theory, contract theory, etc. etc. It is not a "
theory " in terms of industrial organization theory, or microeconomic theory, or international trade theory, or electoral voting theory, spatial voting theory, or ambitions politician theory, or conditional party government theory, or veto power theory, or liberal institutionalism theory, or structural realism theory, or hegemonic stability theory etc. etc..
However all the latter "theories" assume interactions among rational actors with regard to specified choices and hence they all use rational choice theorizing.

2. Of course, why Noda steadfastly chose to pursue the tax hike can be explained by rational choice epistemology, only if one assumes that Noda is acting rationally. The most obvious explanation is that Noda wants to prove that he is a competent leader. This explanation is within the rubric of electoral voting theory which has proven again and again that the median voter votes according to his/her evaluation of the economy (especially in the context of U.S. Presidential elections). Hence, if being viewed as economically competent by the voters is critical in winning an election it is perfectly rational for competing political leaders to advocate and
*realize* such policies. Note that Noda is the third of the last four PMs to advocate tax hikes and that he successfully passed the bill with the cooperation of his major rivals. Why didn't Tanigaki take Ozawa's populist position? Economic voting theory can explain it in three words, "demostrating economic competence."

3. Another theoretical candidate is ambitious politician theory, which expects politicians to clime the party ladder by showing his/her commitment to a certain policy position and winning their support.
Once, you are elected either by the voters or by your college to higher office in the party or legislature, politicians tend to work hard on their pet issues, or lose the trust of their voters or their colleagues and go nowhere in their political career. The fact that ambitions politicians don't pander to public opinion but work hard to win the trust of their colleagues to reach leadership positions have been proven over and over again. Noda was elected party leader and consequently PM on a tax hike platform, if he wants to maintain control of his party (which is pretty shaky) and/or win the trust of his rivals--Tanigaki and
Yamaguchi-- in passing the bill, changing his position will mean losing control of the party and thrust of the opposition, which spells another Kan Naoto.

My bottom line is, I think you need to be versed in political science theories to explain Noda's behavior as a rational being. A crush course in rational choice "theory" just won't cut it.

Nobuhiro Hiwatari