Self-examination is itself a legitimate form of philosophical inquiry

Montaigne's most radical methodological move is treating his own private thoughts, moods, bodily sensations, and trivial daily habits as worthy subjects of serious intellectual investigation, rather than confining philosophy to abstract questions about ethics, metaphysics, or logic. He proceeds by observing himself carefully and reporting what he finds, including contradictions and embarrassing details, trusting that honest particulars about one life can illuminate something genuinely general about human nature.

This was a striking departure from the philosophical conventions of his time, which generally prized systematic argument over personal anecdote and admitted uncertainty. His justification is that since he cannot fully know anyone else's inner life with certainty, his own experience is the one dataset he can examine with real rigor, making it a legitimate, if limited, starting point for broader reflection.

This approach effectively created the personal essay as a distinct form, one where the writer's own uncertain, evolving perspective is the explicit subject rather than something edited out in favor of impersonal authority.

Takeaway: honest, detailed attention to your own experience can be a legitimate route to broader understanding, not merely self-indulgence.