This question touches on one of philosophy's most challenging problems: what makes you 'you'? When a brain tumor causes dramatic personality changes, we face a dilemma about personal identity. Are we defined by our physical bodies, our memories, our personalities, or something else entirely?
The bodily continuity theory suggests that personal identity is tied to physical continuity. From this perspective, as long as the person has the same body, they remain the same individual. Even though the brain tumor causes personality changes, the physical body is largely unchanged. This view is often adopted in legal and medical contexts.
The psychological continuity theory focuses on mental rather than physical continuity. According to this view, what makes you 'you' are your memories, personality traits, values, and consciousness. When a brain tumor causes dramatic changes to these psychological elements, the person may no longer be the same individual in any meaningful sense, even though their body remains largely unchanged.
Brain tumors add a crucial complication to the identity question. Unlike other causes of personality change, a brain tumor has a clear physiological basis. The tumor physically affects brain tissue, which in turn affects consciousness, memory, and personality. This raises the question: are these changes truly representative of the person, or are they symptoms of a disease? The physical cause makes it harder to determine whether we're seeing a different person or the same person affected by illness.
In conclusion, there is no simple answer to whether a person with a brain tumor-induced personality change remains the same person. The answer depends entirely on how we define personal identity. From a physical and legal standpoint, they remain the same individual. From a psychological and relational standpoint, they may be considered a different person. This question highlights the complexity of human identity and remains one of philosophy's most enduring puzzles.