Exposing a child to logical reasoning and analytical thinking from early age helps the child develop his/her brain and create a crucial basis for his/her future ability to learn. Parents need not be convinced that analytical thinking is important to their child's future in school and beyond.
We would like to start teaching children in such a young age for many reasons:
Firstly, we start teaching so early because children like to learn. For many of us, the word "problem" brings to mind unpleasant images - work to be done, worrisome issues to be resolved, and priorities to be sorted out. But this is not the attitude with which we begin life. Solving problems is actually fun for kids. The feeling of meeting a challenge is satisfying at any age, and by providing your child with successful experiences early in life, there is a better chance that he/she will retain a positive attitude as he/she gets older.
Secondly, given the degree to which problem solving pervades every aspect of formal schooling, from astronomy to zoology, a child who takes pleasure in figuring things out is bound to be a better and a happier (!) student. At this age they are still exploring the world around them, and they learn not because they have to, but because they find it interesting.
Thirdly, this is also the best age to start learning. We all know that children absorb new information and skills like a sponge and such knowledge usually stays with them for a long time. The earlier your child learns basic concepts, the better prepared your child will be for the more complicated subjects taught later in school; the better they will "stay" with him or her through the life; the better your child's logical and analytical skills will be in the long term.