Input: Article: Most of Hume's followers have disagreed with his conclusion that belief in an external world is rationally unjustifiable, contending that Hume's own principles implicitly contained the rational justification for such a belief, that is, beyond being content to let the issue rest on human instinct, custom and habit. According to an extreme empiricist theory known as phenomenalism, anticipated by the arguments of both Hume and George Berkeley, a physical object is a kind of construction out of our experiences. Phenomenalism is the view that physical objects, properties, events (whatever is physical) are reducible to mental objects, properties, events. Ultimately, only mental objects, properties, events, exist hence the closely related term subjective idealism. By the phenomenalistic line of thinking, to have a visual experience of a real physical thing is to have an experience of a certain kind of group of experiences. This type of set of experiences possesses a constancy and coherence that is lacking in the set of experiences of which hallucinations, for example, are a part. As John Stuart Mill put it in the mid-19th century, matter is the "permanent possibility of sensation". Mill's empiricism went a significant step beyond Hume in still another respect: in maintaining that induction is necessary for all meaningful knowledge including mathematics. As summarized by D.W. Hamlin:

Now answer this question: What did Hume say can't be rationally justified?

Output: belief in an external world

Input: Article: By mid-1942, the Japanese found themselves holding a vast area from the Indian Ocean to the Central Pacific, even though they lacked the resources to defend or sustain it. Moreover, Combined Fleet doctrine was inadequate to execute the proposed "barrier" defence. Instead, Japan decided on additional attacks in both the south and central Pacific. While she had the element of surprise at Pearl Harbor, Allied codebreakers had now turned the tables. They discovered an attack was planned against Port Moresby; if it fell, Japan would control the seas to the north and west of Australia and could isolate the country. The carrier USS Lexington under Admiral Fletcher joined USS Yorktown and an American-Australian task force to stop the Japanese advance. The resulting Battle of the Coral Sea, fought in May 1942, was the first naval battle in which ships involved never sighted each other and only aircraft were used to attack opposing forces. Although Lexington was sunk and Yorktown seriously damaged, the Japanese lost the carrier Shoho, and suffered extensive damage to Shokaku and heavy losses to the air wing of Zuikaku, both of which missed the operation against Midway the following month. Although Allied losses were heavier than Japanese, the attack on Port Moresby was thwarted and the Japanese invasion force turned back, a strategic victory for the Allies. The Japanese were forced to abandon their attempts to isolate Australia. Moreover, Japan lacked the capacity to replace losses in ships, planes and trained pilots.

Now answer this question: When was the Battle of the Coral Sea fought?

Output: May 1942

Input: Article: Organisms inherit their genes from their parents. Asexual organisms simply inherit a complete copy of their parent's genome. Sexual organisms have two copies of each chromosome because they inherit one complete set from each parent.:1

Now answer this question: Why do sexual organisms have two copies of each chromosome?

Output:
because they inherit one complete set from each parent