3 yr old reasoning abilities

[kelebek]

My DS was 3 in March and has always been verbal since he was 2. He talks to anyone about anything. He has a gerat sense of humour and I can see that he put's things together but whenever we ask him 'why' as in 'why did he do something, why won't he do something, why is he whinging, why is he crying' he often says cause but no real explanation.

I don't like to prompt but find that I am often suggesting trying to help the situation How do I help him to explain himself? I often know instinctually what is wrong but sometimes my partner is the one to be asking him and I think that is not helping

Any ideas/suggestions?
TIA