Should compulsory voting exist?
In the very least, there should be an option to abstain in such a system. This would be serve either as a protest against the choice of candidates given, or against the system itself. So even if you had only one candidate (this sounds familiar *cough*), if more people abstained than voted, that would undermine the idea that his walkover-seat was truly "mandated by the people".
The entire PAP regime is arguably in power due to the compulsory voting system: it is curious how they rose to power only after that was implemented, quickly filling up the vacuum the Labour Front left behind. It could well be most people did not really throw their support behind the PAP, so much as having heard about it, and come election day it was the only thing on the ballot they recognised. And after the PAP had secured power once, they had only need use their state power to consolidate their power and ensure their election victories from then onwards.
If not for compulsory voting, opposition parties would win far more seats in each election than with the present situation; perhaps even oust the PAP. Most of the politically apathetic Singaporeans would not vote, if it weren't required by law. So even in the present, when they get down to the polls, unaware of their rights and the issues, who are they more likey to choose -- a name they have been bombarded with from young, or an opposition party they never took the time to research?
It could well be the entire PAP rule from 1959 has been illegitimate, too. Most of the details of what exactly the PAP did at that time are suspiciously scant (and rather absent from the textbooks). The traditional propaganda paints a romantic picture of the PAP hard at work going door to door to collect votes, but I wonder if the secret of their success has been due to something else?
Low voter turnout is undesirable, because if the government were to be voted in on 10% turnout for example, the mandate would be weak. Most likely, the sheer majority of people do not (actively) support the government. There is little affirmation of consent by the governed. The legitimacy (or even the power, since political power is derived from the majority) of the government is called into question.
Compulsory voting drastically increases voter turnout. But isn't this an easy way out? Arguably, this only enforces a false mandate; in the very least, it only benefits the establishment. An Australian friend once described to me how she would rip her ballot in front of the election officials every election as a form of civil disobedience against the hated compulsory voting law.
If one still wishes to make attending the polls compulsory, there should be an explicit "abstain" (i.e. I hate all the possible candidates) option in the least. Again, this would partly solve the walkover issue for Singapore -- a PAP candidate would have to be explicitly voted for and surpass the "abstained" amount to gain the mandate for that seat.
also posted in the Young Republic mailing list