Here summit means a meeting/conference of several important people Governments often hold summits In your sentence, it means a gathering together of several important people in the field of psychology

A philosophy summit, in the context you've provided, refers to a gathering or conference where individuals interested in philosophy come together to discuss and exchange ideas on various philosophical topics. These events typically feature presentations, lectures, panel discussions, and opportunities for networking and intellectual discourse among philosophers, scholars, students, and enthusiasts. Philosophy summits serve as platforms for sharing and advancing philosophical knowledge and often cover a wide range of subjects within the field of philosophy. Participants may include academics, philosophers, and anyone with a keen interest in philosophical inquiry.

I see two distinct possibilities for what this might mean. The first is the meaning mentioned in the other comments, wherein "Philosophy" is the name of an academic discipline. If that is the intended meaning, then "Philosophy" should be capitalized since it is being used as a proper name. The second meaning is the one wherein "philosophy" is being used as an adjective to modify "summit". In that case it should not be capitalized. It could still mean an academic meeting to discuss the academic subject Philosophy, but it doesn't have to mean that. That is because "philosophy" has another meaning. It can also refer to a set of fundamental ideas about just about anything. For example, if you are a person who earns a living by coaching athletes, you may have a "philosophy of sports" that helps you to organize your thoughts about how that should be done. If you meet in Lisbon with a group of like-minded people to exchange ideas about their philosophy of sports, it would not be wrong refer to that as your "philosophy summit".