Subject-Object Asymmetries of Topics in Japanese

This paper aims to syntactically explore subject-object asymmetries of (thematic) topics in Japanese. In particular, I observe that in Japanese, a subject topic and an object topic can co-occur in the same clause, but that the latter must precede the former. Based on this observation, I propose that there are two topic projections in Japanese, and that the higher projection hosts an object topic, while the lower one hosts a subject topic. I then investigate each of these two projections in more detail: Regarding the higher topic projection, I argue that it can host not only an object topic but also a gapless topic. Regarding the lower topic projection, I claim that it is A/A'P, a projection proposed by Bošković (2024a,b) which has mixed A- and A'-properties. This claim gives an account of the word order asymmetry between a subject topic and an object topic.