個人のケイパビリティは，本人の利用可能な「資源」と「利用能力」のもとで，可能となる「選択の実質的機会」として定義される．本稿は，この個人のケイパビリティを，選択との内在的関係に留意しながら同定する方法を探った．分析結果は3点に集約される．【1】諸機能の内在的価値を評価しうる「ケイパビリティ制約付き最適化モデル」は，伝統的な「資源制約付き最適化モデル」とは異なる最適化条件をもたらす．【2】ただし，個人の選択を自律的・責任的要因と見なす限り，前者もまた，本人の選好評価から独立に，本人が客観的に獲得できたはずのケイパビリティを政策的基礎とすべきだという議論を無条件に正当化するおそれがある．【3】だが，個人の選択には「個別主観性」と「位置主観性=客観性」の2側面があり，後者に関しては，自律と責任を無条件に仮定することはできない．以上の分析を通じて，本稿は，個人の自律と責任，アイデンティティと自由に関する従来の研究に新たな知見を加えた．A capability is defined as the set of alternatives (substantive opportunity), from which an individual can actually choose and have reason to choose, given certain resources and skills, based on her own evaluation. Yet, how should we judge whether or not she can really choose? What are the criteria to distinguish an individual's choice from her capability, the shortage of which can legitimately be addressed of social policies? This is the question of the identification of an individual's capability. The results are as follows. (1) The "maximization model with capability constraints" brings about solutions which satisfy the Pareto efficiency in capability space, rather than in the traditional resource space). (2) With the concept of positional objectivity, we can insist that except in the case where it is derived from the individual's subjectivity and individuality, called "pure subjectivity", an individual's choice can also be a constituent of capability as an informational bases of social policy.