意志 and 意思: two spellings of いし and a person's wishes
Compare 意志 and 意思 through strong will, expressed intentions, and confirmation of a person's wishes. Read their overlap alongside the difference between a past participation decision and a scheduling proposal.
One reading with overlapping meanings
Both 意志 and 意思 are read いし. 意志 includes will and intention, while 意思 includes intention and will. The examples overlap in confirming a person's own wishes, so an absolute split between an inner will and an outwardly expressed intention does not fit all of them.
「困難があっても学び続ける強い意志を持っている。」 describes a strong will to keep learning despite difficulties. 「彼女は最後まで参加する意思をはっきり示した。」 means “She clearly expressed her intention to participate through the end.” These examples show continued determination and a clearly expressed intention to participate.
Confirming someone's wishes with either spelling
「本人の意志を確かめてから参加を決めた。」 means “We decided on participation after confirming the person's own wishes.” This uses 意志 in a scene where the person's wishes are confirmed. Treating 意志 as something that can never be checked or communicated would conflict with this example.
「本人の意思を確認してから日程を決めよう。」 means “Let us confirm the person's wishes before deciding the schedule.” Confirmation of the person's wishes overlaps with the 意志 example. However, the first sentence reports a past participation decision, while this one proposes how to decide a schedule.
Reading the context beyond the spelling
Keep the strong will to continue learning and the expressed intention to participate in view, while also remembering that both spellings occur with confirmation of wishes. The examples do not support a rule that 意志 always means stronger will and 意思 always means weaker will. Read what the person wants and what others are confirming.
A past decision on participation is different from a proposal to decide a schedule after checking someone's wishes. Preserve that difference in action and timing when comparing the sentences. Specialized legal, philosophical, or psychological definitions are not needed to explain these examples.
Does a scene involving confirmation of someone's wishes require the spelling 意思 alone?
Show the answer and why
No. The material uses 意志 when participation was decided after confirming the person's wishes, and 意思 in a proposal to confirm wishes before deciding a schedule. Their meanings overlap here; the past decision and the proposal still need to be read separately.