When Japan shifted its diplomatic recognition from the ROC to the PRC, it recognized the latter as the “sole legal government of China.” Given that Japan was not recognizing China as a new state – international recognition of the Chinese state had existed without interruption since the ROC government emerged in 1912 – the PRC effectively accepted the rights and obligations of the previous government.
可以肯定，旧金山条约本身对中华人民共和国并不具有法律效力。但是对日本而言，正像1972年日中联合公报所表明的那样，中华人民共和国显然取代了台湾中华民国的合法地位，而六年后又在日中联合公报的基础上签署了日中和平友好条约。当日本从中华民国转而承认中华人民共和国的时候，它明确后者才是“中国唯一的合法政府”。鉴于从1912年中华民国成立后中国就一直是国际承认的主权国家，也就是说日本并未承认中国的新国家地位——中华人民共和国实际上接手了上届政府的权利和义务。