Is sanity rational?

[genkaus]

Except maybe not. For example, we may have an exaggerated fear response when faced with uncertainty (e.g. in the dark). To perceive a greater probability of a wild beastie being present behind a tree than actually exists in reality may enhance survival. The statistician David Spiegelhalter has all sorts of interesting anecdotes on how poor we are at perceiving likelihood of events. And this is something Alvin Plantinga has thought and written about: that evolution need not necessarily drive accurate perception of the world around us; there may be indeed be evolutionary advantages to a distorted sense of reality. And it goes back to that ancient philosophical problem: how can I be sure that I'm not hallucinating?

That is why my argument came with a caveat : "That is the criteria for a sound and healthy mind - one that is capable of drawing a representation of reality with a certain basic degree of accuracy."

Imagining a beastie behind a tree occasionally is not a significant distortion in the mental representation - so, its within acceptable bounds. However, if you start imagining beasties behind every tree, that is a significant distortion which would diminish survivability.

Contrary to what Platinga says, distortions in the perception of reality can be advantageous only if they are to a minor degree. Any major distortions won't be advantageous. Which is why evolution would drive you to build a mostly accurate perception even if there are a few advantageous distortions thrown in. Thus the answer to the ancient philosophical question : check if what you see fits with the rest of what you know about reality.

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In my opinion, altruism is more sane than self-preservation, even though it is probably also an evolved emotional mechanism. It shows that despite one's evolved feelings of self-importance, one is aware on some level that one really ain't all that.

Given the vastness of the universe, and the number of people alive, I think it's highly delusional to protect one's self, especially at a risk or deliberate harm to others; this behavior indicates a belief, at least at the level of instinct, that one is a special snowflake. I don't think any individual's life memories, knowledge or world view is likely to be so unique and important that it's worth saving. And even if you happen to be an Einstein, it's hard to argue that in a universe with trillions of stars, even the welfare of the entire human species (or life on Earth) is likely to matter much.

The key question you are ignoring here is "matter to whom?". The arguments you make for the ultimate irrelevancy of individual life are irrelevant - one's life and actions are relevant to oneself.