The question has a biological answer and no other kind is available

The argument

Proponents of this position argue that the question only looks deep because it borrows a form of words from contexts where purposes really do exist. We ask why a tool exists and the answer names its maker's intention; we ask why a meeting exists and the answer names what it is for. Applied to living things, they argue, the question has a perfectly good answer of a different kind: a lineage exists because each generation in it managed to produce the next. That is not a disappointing substitute for a real answer. It is the answer, and it is the only one the subject matter supports. Holders of the view press the point that this explains the features of ourselves that most need explaining. Our bodies, appetites, attachments and even much of what we find beautiful or repellent make sense as equipment for surviving long enough to reproduce and for raising offspring that do the same. Nothing else proposed as a purpose for human life has anything like this explanatory reach: it is not clear what a spiritual purpose would predict about teeth, or about why the young are more fertile than the old, whereas the reproductive account predicts both. Defenders of the position usually add a clarification, since the position is often read as a recommendation. To say that we exist to procreate is to say what the existence of the species is explained by, not to say that any individual is obliged to have children or that a childless life is a failure. The purpose is a property of the lineage rather than a duty laid on its members. What follows for an individual, on this account, is only that the search for some further purpose behind their existence is looking for something the record does not contain.

Premises

Counter-arguments

Critics argue that the position answers a different question from the one asked. Explaining how a lineage persisted says nothing about why anything should be here to persist, and the word purpose has quietly changed sense between the two. They also press the gap the position itself concedes: if the purpose belongs to the lineage and lays no duty on anyone, then it offers no answer at all to the person asking why they exist. Others object that human beings routinely act against reproductive interest and regard some of those acts as among their finest, which is hard to square with reproduction as the point.

Rejecting the premises

[Rejecting P1] Asking why we exist need not be asking what brought us about, and if it is the other question then the biological answer changes the subject rather than answering it. [Rejecting P3] That no alternative has been established is not evidence that none is available, and the position offers no argument that the search has been exhausted. [Rejecting C] A purpose that belongs to a lineage and binds none of its members does not answer the question any individual is asking when they ask why they exist.