The nihilist attitude manifests a certain truth. In this attitude one experiences the ambiguity of the human condition. But the mistake is that it defines man not as the positive existence of a lack, but as a lack at the heart of existence, whereas the truth is that existence is not a lack as such. And if freedom i experienced in this case in the form of rejection, it is not genuinely fulfilled. The nihilist is right in thinking that the world possesses no justification and that he himself is nothing. But he forgets that it is up to him to justify the world and to make himself exist validly. Instead of integrating death into life, he sees in it the only truth of the life which appears to him as a disguised death. However, there is life, and the nihilist knows that he is alive. That’s where his failure lies. He rejects existence without managing to eliminate it. He denies any meaning to his transcendence, and yet he transcends himself. A man who delights in freedom can find an ally in the nihilist because they contest the serious world together, but he also sees in him an enemy of the world and man, and if this rejection ends up in a positive desire for destruction, it then establishes a tyranny which freedom must stand up against.
The fundamental fault of the nihilist is that, challenging all given values, he does not find, beyond their ruin, the importance of that universal, absolute end which freedom itself is. It is possible that, even in this failure, a man may nevertheless keep his taste for an existence which he originally felt as a joy. Hoping for no justification, he will nevertheless take delight in living. He will not turn aside from things which he does not believe in. He will seek a pretext from them for a gratuitous display of activity. Such a man is what is generally called an adventurer. He throws himself into his undertakings with zest, into exploration, conquest, war, speculation, love, politics, but he does not attach himself to the end of which he aims; only to his conquest. He likes action for its own sake. He finds joy in spreading through the world a freedom which remains indifferent to its content. Whether the taste for adventure appears to be based on nihilistic despair or whether it is born directly from the experience of the happy days of childhood, it always implies that freedom is realized as an independence in regard to the serious world and that, on the other hand, the ambiguity of existence is felt not as a lack but in its positive aspect.
From the time of his adolescence a man can de fine himself as an adventurer. The union of an original, abundant vitality and a reflective scepticism will particularly lead to this choice.
It is obvious that this choice is very close to a genuinely moral attitude. The adventurer does not propose to be; he deliberately makes himself a lack of being; he aims expressly at existence; though engaged in his undertaking, he is at the same time detached from his goal. Whether he succeeds or fails, he goes right ahead throwing himself into a new enterprise to which he will give himself with the same indifferent ardour. It is not from things that he expects the justification of his choices. Considering such behaviour at the moment of its subjectivity, we see that it conforms to the requirements of ethics, and if existentialism were solipsistic, as is generally claimed, it would have to regard the adventurer as its perfect hero.Simone de Beauvoir (1948) The Ethics of Ambiguity, pp 57-59.