You can't reason with a preschooler

I don't know how many times I've been in a store when I've heard a frazzled mother try to reason with an out-of-control 3 year old.  It just isn't going to work, lady.  Children aren't miniature adults.  They go through fairly predictable stages of growth and development from the time they are newborn and far into adulthood.  The ability to reason doesn't happen until the child is somewhere around the age of 8.  Until then, short, sweet statements of what you expect from your preschooler work better than long drawn out lectures.  Also, it's better to be specific rather than vague.  Example...say "Don't hit your brother!", not "Stop that!"  Neither should you ask why.  Most likely, the only real reason why is because he or she felt like it at the moment.  Kids are impulsive.  Be clear.  Be firm.  Be specific.  Be consistent.  And don't issue threats you aren't willing to carry out.  Your child will get the message...eventually.