You may have been in a situation in which a motivational speaker holds up a glass with water to approximately the halfway level and he/she asks his/her audience “is the glass half-full or half-empty?” I first came across this question in high school. My English teacher sketched what appeared to be a glass with water on the chalk board and asked the class to describe it. I was lost. I don’t remember what my first thought was. That was also the first time I heard about ‘optimism’ and ‘pessimism’.
In such a motivational speaking session, the motivational speaker’s test is meant to show that one can either view a situation or circumstance either pessimistic ally or optimistically. But does it? Not necessarily. In the instance that the question is asked, it does not make logical sense. In this case, this question is a non sequitur. In a non sequitur, the argument is fallacious because the conclusion does not logically follow from the situation presented, regardless of whether the conclusion is true or false.
Now, let us consider a scenario in which the same motivational speaker (bless motivational speakers) has two glasses – a glass full of water in her left hand and another empty glass in her right hand. She then pours half the water from the full glass to the empty glass. You now have one half-full glass and another half-empty glass.
Assume that the motivational speaker moves the glasses about very fast and then asks the question, “which glass is half-empty and which glass is half-full?” You would only guess and there would be a fifty per cent chance that you would be right. As you can see, without knowing the previous state of the glasses, the question would be non sequitur.
Another misconception brought about by the motivational speaker’s talk after the question above is that an optimistic view of circumstances/situations is the more desirable outlook. But again, is it? Not necessarily.
Let us consider another case scenario. A man driving in an isolated countryside notices that his fuel gauge reads close to ‘empty’. He notices a small town along the way he is driving which is about ten kilometers to his destination. The pessimist (doubting whether the he could possibly drive the 10km with that fuel) drives into the town and tops up his gas but the optimist drives on hoping that he will reach his destination before the fuel runs out. The pessimist gets to his destination in time whereas the optimist gets stuck up along the way. The assumption that an optimistic view is better than a pessimistic view is also non sequitur.