That is not true. There are plenty of ways not to reproduce and still to perpetuate your genetics. For example, if you don't have children of your own, but support people that have similar genetic traits to your own.
This is sometimes referred to as the “grandmother effect” in sexually reproducing species. The evidence in favor i still weak even in humans due to our low effective population size. I am not sure that there is good empirical support in other species, even eusocial insects.
If i support my brothers / sisters children, but have no children of my own, genetic data of mine survives into future generations, after all I share half my genetic data with my siblings.
If my helping these children gives them a competitive advantage in further reproduction, where the total reproductive strength of these well supported kids is greater than the total reproductive strength my family would have if I had my own children as well and split our resources, then this behaviour outcompetes simple reproduction, and if this behaviour is genetically encoded, becomes a dominant trait over time.
Yes, but population genetics is complicated. Selection pressure does not operate well wgen effective population sample sizes are small and when environments are noisy. Evolutionary drift is a major force. Supporting a cousin or three will not gain your genes much.
Fitness of what? If you mean the genes, then a gene may have more copies made of it if it causes some of its carriers to assist other carriers of the same genes in ways that help them produce, rather than reproducing individually.
I described fitness of genes, yes. Previously it seemed like you were saying that an individual of a species had low(zero) fitness if that individual doesn’t reproduce. Further, you seemed to imply that this was the relevant measure, seemingly to say so as a counterpoint to the point that an individual can act in a way that helps to propagate genes that that individual carries without actually reproducing.
It appears that some miscommunication occurred, which may have been me being dense or misinterpreting. Do you know where this miscommunication occurred?
The word “word”, as usually used, is not a term which is defined to only apply to things which have definitions.
Generally one can describe how people use a word. (Though, see “semantic primes”; there has to be some cycles in what words are defined using what words.)
I think the quotations around “define” were intentional in the comment you replied to. I think their point wasn’t to say something like the “undefinability of truth” paradox (the whole “truth is in the metalanguage” thing), but to say that it seemed to them that you were kind of sneaking in assumptions as part of definitions, or something like that, idk.
