Final answer:
McKinley believed annexing the Philippines was justified due to economic, military, and cultural reasons.
Step-by-step explanation:
McKinley believed there were three main reasons to justify annexing the Philippines: economic reasons, military considerations, and cultural obligations. Economically, McKinley believed that acquiring the Philippines would provide new markets for American goods and open up trade routes in the Pacific. Militarily, he saw the Philippines as a strategic location for establishing a naval base in Asia. Culturally, McKinley believed that the United States had a duty to bring education, Christianity, and civilization to the Filipino people.
Learn more about Reasons for annexing the Philippines