subject position in (38a), neither John nor its trace (copy) t can move into
another Case position, as shown in (38b).
(38) a. ___ seems that [α(=TP) John will [β(=vP) t meet Mary]]
b. ∗[Σ John seems that [α(=TP) t’ will [β(=vP) t meet Mary]]]
Since John already checks its Case in α, it cannot move into another Case posi-
tion, resulting in the immobility of John from t’ in (38b). See Narita and Fukui
(2016) for an account of the relevant fact in terms of their “Equilibrium Intact-
ness Condition.” See also Rizzi (2006) for the notion of “Subject Criterion.”
However, these authors have nothing to say concerning why the lower occur-
rence of John within β (indicated by t) can never move, skipping over the other
occurrence in t’ in (38b).^26 We argue that our minimality condition in (32) can
explain this state of affairs: M 0 ◦S 0 (WS) cannot generate {Σ, β}, because there
exists an SO α such that {Σ, α} also meets the formal restriction on Chain and
Depth(α) < Depth(β); hence, α is closer to Σ than β.
Finally, let us turn to Merge, understood here as another instance of
M 0 ◦S 0 (WS). It combines two SOs (lexical or constructed) within WS, α and β,
and creates a new SO {α, β}. We take the primary function of Merge to be
formation of a new sister relation. We can defi ne Sister in terms of structural
prominence discussed in (31).
(39) Sister:
{α, β} may count as an instance of Sister only if Depth(α) = Depth(β).
Each application of Merge(α, β) creates a new SO {α, β}, and this new SO is
added to WS. Since {α, β} is by defi nition not dominated by any other SO in
WS so long as the NTC is satisfi ed, Depth(α) = Depth(β) = 1 holds for every
instance of Merge(α, β) = M 0 ◦S 0 (WS) = {α, β} (see note 19).
Now we should ask if this form of M 0 ◦S 0 satisfi es the minimality condition
in (32). Consider (40) below:
(40) Σ = {John, {v, {buy, what}}}
At fi rst sight, IM of what to the edge of Σ appears to be blocked by the exis-
tence of, for example, v: {Σ, v} would satisfy the formal restriction in (39) and
Depth(v) < Depth(what) in (40). This problem will be resolved if Depth(γ)
and Depth(β) in (32b) are interpreted as “Depth(γ) when {α, γ} meets the
relevant formal restrictions” and “Depth(β) when {α, β} meets the relevant
formal restrictions,” respectively. Under this assumption, Depth(what) and
Depth(v) for the application of IM of what in (40) are calculated not based on
(40), but based on (41a) and (41b), respectively:
(41) a. {what, {John, {v, {buy, what}}}}
b. {v, {John {v, {buy, what}}}}
40 Takaomi Kato et al.