一個雙層雙重式比例代表制：從演化觀點啟發的選制改革提議

在複數選區採用「類別選票」的情況下，為了減少策略投票，除了要追求政黨層次比例代表性外，也應追求候選人層次比例代表性。因此，根據優生學的概念，本文提出一個使用黑爾／尼邁耶最大餘數法的雙層雙重式比例代表制，透過區域與不分區之雙層設計達成政黨與候選人之雙重比例代表性。作法是，藉由分散且開放式的不分區名單，取代現行集中且封閉式的政黨不分區名單；將政黨所贏得之不分區席次，根據該政黨內所有跨越分席門檻之候選人在低層次選區之得票數，按比例分配給與其搭配的不分區候選人，以達成候選人層次之比例代表性，並落實「票票等值」的精神。簡言之，雙層雙重式比例代表制就各個低層次選區而言（即區域代表之分配方式），政黨間（含獨立參選人）採取的是比例代表制而政黨內採取的是相對多數決制；就高層次選區而言（即不分區代表之分配方式），政黨間（跨越政黨分席門檻者）與政黨內（跨越候選人分席門檻者）均採取比例代表制。透過電腦模擬，以第六屆立法委員選舉的實際資料為依據，結果顯示新選制確實比單記非讓渡制更具政黨層次的比例代表性，且具有相當程度的候選人層次比例代表性。

關鍵字

比例代表制；策略投票；黑爾／尼邁耶最大餘數法；選舉制度；優生學；單記非讓渡制

並列摘要

In multi-member district with categorical ballots, for reducing strategic voting, what we should aspire to is not only party-level proportionality but also candidate-level proportionality. According to the concept of eugenics, we propose a two-tier dual proportional representation system. The ＂two-tier＂ means lower level district versus higher level district, and the ＂dual＂ refers to party-level versus candidate-level. By using a distributed open list that is comprised of several candidate-affiliate lists to supersede a centralized closed list that is under control by the political party, the proposed electoral system applies the Hare-Niemeyer Largest Remainders (HNLR) method, according to the votes received by those candidates who crossed threshold in a lower level district, to apportion the supplementary seats a party has won among individual(s) of the candidate-affiliate lists to ensure candidate-level proportionality and to fulfill “one vote, one value” esprit. In short, in lower level districts, the new electoral system applies proportional representation system to inter-party (including those independent candidates) and applies plurality system to intra-party; in higher level district, the proposed electoral system applies proportional representation system to both inter-party (have to cross a threshold) and intra-party (have to cross a threshold). That is why we call it a two-tier dual proportional representation system. By using computer-aided simulations with the voting data of the sixth legislative election, we demonstrate that the proposed electoral system possesses more party-level proportionality than the SNTV does and that the proposed electoral system exhibits candidate-level proportionality to a certain high degree.

並列關鍵字

Proportional Representation System ； Strategic Voting ； Hare-Niemeyer Largest Remainders Method ； Electoral System ； Eugenics ； Single Non- Transferable Vote