narrow partisanship; factionalism
A yojijukugo describing the tendency to side with one's own faction and attack those who differ. Often used in political or organizational contexts to criticize blind loyalty and exclusion of outsiders.
Politics driven by narrow partisanship loses the public's trust.
あの組織は党同伐異の傾向が強く、新しい意見が通りにくい。
That organization has a strong tendency toward factionalism, making it hard for new ideas to be accepted.
派閥主義 refers more concretely to faction-based politics or cliquishness within a group, while 党同伐異 emphasizes the aggressive exclusion of those outside one's faction.
仲間意識 is a neutral or positive term for camaraderie or in-group feeling, whereas 党同伐異 carries a strong negative connotation of attacking outsiders.
A yojijukugo derived from classical Chinese, combining 党 (faction), 同 (same), 伐 (attack), and 異 (different). The phrase originally described the practice of favoring one's own group and attacking those who are different.