Commonsense being hard.

 Minsky says that commonsense is hard.“Commonsense is not a simple thing. Instead, it is an immense society of hard-earned practical ideas - of multitudes of life-learned rules and exceptions, dispositions and tendencies, balances and checks.”(Pg.22, The Society of Mind, Heinemann : London, 1985).

Consider this piece of commonsense - If you use a cab, you will have to pay rent at the end.

The reason why most of this simple knowledge-piece like the one above is hard is that “there is so much” in each piece. When you are talking about a cab, there is so much to a cab. There are so many aspects to it - its parts, processes associated with it, its properties etc. There is the main body made of steel/iron, there are doors, handles, seats, windows, engine, carrier etc. As far as using a cab is concerned, there is the opening of the door, the sitting inside, the actual traveling journey, the talking to the driver about the route, the other things about your life you have in mind which go through it, the goods you are carrying,the people you are along with etc. You are exposed to so much while traveling (which you see through the window as a flow coming at you). You observe the driving of the driver, you experience moving through space automatically, you observe the route you are going along... All this is what is there to a ‘cab’ and to ‘using it’. There is so much possible. So many aspects of each entity involved can be connected to those of the others, leading to various possible thoughts, possibilities, conjectures, concepts and ideas. Out of these just the right, few, precise aspects have to be looked at and picked up to connect with each other, to arrive at the piece - using a cab implies paying rent at end. Here, only the“sitting in the cab while the driver serves you by driving, and your relocation/transfer via the journey” are the important facts connected to the service offered and experience gone through for which you have to pay the charges. If you keep your mind ONLY to this precise set of connected things, it is pretty simple to realise that commonsense fact, even for machines. But that's not the case in real life. The actual experience of going through picking up a cab and finally reaching the destination is made up of such 100-odd things that it is indeed a special cognitive process to keep track of the essentials - the “few, precise and right” - factors to smoothly process, connect and conclude and execute the realisation (before, during and at the end) that at the end, according to the journey, there is FARE PAYMENT.

‘A is taller than B and B is taller than C implies that A is taller than C’ is indeed easy. (So is ‘1+1=2’) This is not hard for humans (as well as machines). This, even though is commonsense, isn’t hard-earned (as Minsky says) since here, there isn't much to everything that’s in there - A, B, C, tallness and greater/lesser comparison between 2 at a time. Moreover, everything is precisely defined. Also,there aren’t many and/or multiply vague aspects to A, B, C, tallness and the comparative inequalities. This makes it less “things to handle on the plate”. You don’t have to focus on just the apt right, few, precise set of connected aspects to arrive at the conclusion. And this is how logic is in general. There is nothing “extra” to lead to the world of other possibilities of probable thoughts, conjectures, fall-outs etc via various combinations of the aspects of the entities involved in the whole picture.

“Common Logic” is easy and “Common Sense” is hard, for humans.