This is a very interesting thread. I think this question of 'instinct' is important to address and I see it used as an argument for early weaning more and more. There seems to be a perception that by following an 'instinct' a mother is responding naturally and intuitively to her child and this can only be a good thing, right? In other situations we are told our instinct trumps guidelines. The mother that posts on here saying 'something's not quite right with dd's motor skills' when the hcps have declared all to be well or 'I'm pregnant and something feels wrong' when a midwife says all is fine is told to listen to that all important instinct and rightly so. I fail to see the correlation with weaning. As many on here have said, there is no way to know a baby is ready for food until the developmental signs allow a child to help themselves to food, chew it and swallow it. You can know they're hungrier than normal but the leap to earlier weaning is tenuous at best.
It's a bit of a terrible analogy, but I see it often with pregnancy threads and mothers wanting to bring on their labour when the fact is, the baby will be born when it is ready. Of course some babies will want and indeed need to come early but generally trying to bring on labour is fruitless and induction is so fraught with problems because that baby simply wasn't ready. Of course this desire to hurry things along is only one aspect.
Mothers often seem to believe that their milk isn't enough and I read too frequently that they believe their babies 'need more'. In particular this 'big baby' issue is troubling. If a baby is big then the pressure to wean is enormous. DD was off the charts and 24lb+ at 6 months. Instead of being congratulated that my milk had done a grand job and caused dd to thrive, the party line was 'oh she'll need more than milk'. This undermining negativity is rife it would seem (from reading MN, talking to friends) and when you couple a mother who is told she'll need to wean early by everybody from HVs to friends with a veritable chorus of 'I weaned early and dc is perfectly healthy', we create a dangerous situation I believe. Already mum believes that her milk isn't enough and the general consensus seems to be that there's something to do to help and anecdotal evidence seems to point to it being right and after all it's only a guideline. So many factors combine and early weaning happens again.
I would say for me that 'instinct' told me dd was hungry, no more, no less. Common sense told me that the most calorific thing for her was breastmilk. Of course at 4/5 months dd went through vast developmental changes. She physically matured, started rolling more, trying to sit, engaging more,thinking very hard indeed and she was extremely hungry as a result. I fed on demand so unrestricted access to the breast saw her through this. I wonder sometimes if the way we parent/feed our children leads to mixed messages. Particularly with routine-based feeds there may be more scope to say 's/he's still hungry after his/her feed'. If demand fed then feeds often seem to be an ongoing affair from morning till night and instinct in that situation told me to allow dd unfettered access because her own survival instinct told her how much she needed.
My sil is currently weaning at 14 weeks and a discussion the other day revealed a fundamental difference in our approach. I wholeheartedly believe that weaning is a developmental thing like walking and talking. SIL thinks it is a hunger issue. Her dd is hungry on 4 hourly feeds so must need weaning. Quite apart from baby or parent led weaning, fact based weaning tells me that yes her dd is hungry, no her gut probably isn't mature, no baby rice will do her no good, yes it may do her harm and yes more breastmilk will provide lots of calories. To me, in that situation, the answer seems obvious.
Sorry I'm wittering and contributing little. You've just got me thinking out loud.