Is the marriage contract valid without a guardian (Wali)?

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Marriage is not valid except with a guardian; a woman cannot contract herself or another in marriage, nor appoint an agent for her guardian to contract her. If she does so, the marriage is invalid. This position is held by Umar, Ali, Ibn Mas'ud, Ibn Abbas, Abu Hurayrah, Aisha (may Allah be pleased with them), as well as Sa'id ibn al-Musayyib, Al-Hasan, Umar ibn Abd al-Aziz, Jabir ibn Zayd, Al-Thawri, Ibn Abi Layla, Ibn Shubrumah, Ibn al-Mubarak, Ubayd Allah al-Anbari, Al-Shafi'i, Ishaq, and Abu Ubayd. The definitive evidence is the Prophet's statement, 'There is no marriage except with a guardian,' narrated by Aisha, Abu Musa, and Ibn Abbas. Furthermore, another narration states, 'Any woman who marries herself without the permission of her guardian, her marriage is void, void, void.' The rationale for prohibiting a woman from contracting marriage independently is to protect her due to perceived deficiency in intellect, preventing potential harm or misconduct. The ruling is affirmed by the general Hadith 'There is no marriage except with a guardian,' which takes precedence over arguments derived from the interpretation of specific verses.