Manipulating Kzin evolution and maybe human evolution too, in such a way it benefits them. I read them as willing to exterminate a whole species if it's for the benefit of theirs. So yes, they are the biggest assholes, the Pak are acting due to their instincts, the Puppeteers do the same or worst in a purelly rational way.
Did the Puppeteers have anything to do with the extinction of the Pak? I wouldn't put it past them.
First principles are never rational. Our needs and desires are set by instinct, not reason. That's true for us, it's true for the Pak, and it's almost certainly true for the Pupeeteers. And of the three, the Pak, not the Puppeteers, are the most completely and purely rational, when it comes to fulfilling their desires. The Pak are just a bit more absolutist about it.
Also, the Pak are never going to be extinct as long as humanity, including the Ringworld clade, exists. Tree of Life is just too good as a secret weapon. If humanity runs into an existential threat, sterilize a few colonies and turn all the eligible adults into Pak, and sic them on the threat du jour. Combined with the Teela gene, the Puppeteers must be really glad that humans are fairly friendly.
Star Trek and Known Space probably aren't a bad mix. They're not directly compatible, but Star Trek is fundamentally about exploration so it's designed for stand-alone encounters, and KS has a lot of elements that can be adopted piecemeal, and which can be used to raise difficult philosophical quandaries and instigate interesting conflicts.
Known Space also has the better aliens.
The Pak are very intelligent and rational but driven by instincts, they must protect their descendants, and if their descendants die they stop eating.
A species that manages to cooperate better than them must be considered more rational.
I think cooperation is less rational.
Think of it this way. The selfish gene, or the idea that evolution optimizes toward each individual maximizing the survival of their genome, is remarkably well supported. There was this idea that certain species evolved collectively, and that individuals would sacrifice their own reproductive utility for the betterment of the group. It seemed to make sense, and fit certain human preconceptions about how the world should work. But as they looked at case after case, they were able to knock each of them down. It didn't hold up, anywhere, except for eusocial insects. So the idea of collective evolution was pretty much annihilated.
The Pak is the ideal of the selfish gene. They're completely, and exclusively focused on the survival of their lineage. That's a purely rational reaction to a primal urge. There's nothing extraneous. No art, no frivolousness. Just a complete obsession on one thing, using their super-human and even super-Puppeteer intellects.
Cooperation requires betraying that base urge. It requires certain individuals sacrificing their own best interest, for the sake of the group. Yes, it can lead to better results for the group as a whole. The Pak homeworld was wracked by war, while other more cooperative species (there's growing evidence that humans may be eusocial; an exception to the selfish gene) spread and flourished. But those results are contingent on individual failures, and if you have the urge to preserve your germ line, then acting in a way that dooms it, is irrational.
So, instead of constantly plotting against other protectors and rendering the land uninhabitable (they did so in the Ringworld too) their best bet to preserve their lineages would be to pool their intelects towards that goal.
By not doing so they show irrational behaviour that's governed by their instincts and or passions not their reason.
On the other hand the Puppeteers cooperate among themselves and with other useful inteligent species, thus maximizing their survavility.
Nessus survives his trip to Ringworld thanks to the loyalty of the humans and Kzin.
A pak is unable to work with other species, he must destroy them. The Puppeteers will destroy only those they can't cooperate with. A much more rational approach.
No, it's not irrational behavior. The irrational behavior is
trust.
The iterated prisoner's dilemma is effectively a model for cooperation among selfish individuals, so it's a pretty good abstraction of evolutionary behavior. And it can tell us the winning strategies, which tend to be variations on tit for tat. That's a type of cooperation. But it's also assuming infinite iterations. If it's a finite series, which it will always be, because we don't live forever, the most optimal behavior for the final iteration is betrayal. We see that among humans, but it's pretty uncommon, when game theory tells us it should be the way every relationship ends.
Not only that, but the tit for tat strategies are very weak forms of cooperation, compared to real human cooperation. We do punish people, but very rarely considering the opportunities and population size. In a social milieu like that, even a small percentage of bad actors or free riders would break the system. But the number of sociopaths who do take advantage is even smaller than that, small enough that the system functions. Humans exhibit an extraordinary degree of a cooperation, without the expectation of reciprocation. The degree is far beyond that exhibited by other animals, or expected from simple game theory analysis of evolution.
It requires humans to sacrifice for an abstract that has nothing to do with the propagation of their genes, and to do so regularly. If your motive is to spread your genes, which is the most fundamental motive of any species shaped by evolution, then that degree of cooperation is irrational from the perspective of any individual. You want
everyone else to behave like that, but it makes no logical sense for you to behave like that. It gains you, and your goal, nothing.
Furthermore, if you look at the origins of social behavior, it's all completely irrational. We're tied together by things like religion, or ecstatic dancing, or waving a flag. None of these are optimal behaviors, from the standpoint of the individual. If you create the perfectly logical being, and give him the basic evolutionary impulse, that being will never engage in any of those behaviors.
Sure, in the long run, those irrational behaviors that lead to high degrees of cooperation will win. But if everyone's acting logically, you'll be stuck in a suboptimal Nash equilibrium, with no way to make the jump.
That's why less logical behavior is important. We need art, we need play, because it allows us to break out of that dog-eat-dog world, and achieve things beyond those who simply take the most logically direct route based on their own needs.