[MENTION=27014]florpoetis[/MENTION] I think oftentimes with instincts, it's very easy for us to confuse/blend core and wing traits in with our understandings of instincts, and really get too caught up in "trait descriptions" in general (that really have nothing to do with the meaning of instincts). For myself, I think it's helpful to understand instincts for what they are alone, in addition to th core specific combinations.
The Social instinct tends to be most focused on
contribution-- to the group, whatever that may be. In 4's this tends to manifest as a fixation with an inability to contribute to the group, almost bemoaning (vocally) the lack of the contribution/involvement that they wish they could make. The Sexual instinct on the other hand is more about merging, moving towards individuals, and manifests in 4's like vengeful envy-- "I envy you, so I kill you" as Naranjo puts it, or making others suffer.
I do think the core specific instinctual descriptions are great and important too. With 4, the general theme is suffering: SO suffers vocally, SP is long suffering, and SX makes others suffer. Here's some work I've done on the instincts of
4 and
3 if it helps at all (I do think looking at wing helps too).