There is a theory that states that there are two kinds of people in the world - the kind that sees the glass as half-full, and the kind that sees the glass as half-empty.

There is another theory that states that there are two kinds of people in the world - the kind who believe that there are two kinds of people in the world, and the kind who don't.

There is a third theory that states that both of the first two theories were created by the former Editor of h2g2, in order to tie up Researchers in philosophical discussion while he got himself another drink.

I wouldn't say 'the glass is half-empty'.
I wouldn't say 'the glass is half-full'.
I might say 'the glass contains 284ml'. If it's a pint pot.
Engineers, eh?

The Dogma is Half-convincing

The more common view is that people who see such a glass as half-full are optimistic, because they are focusing on the half of the glass that contains amber nectar¹. On the other hand, people who see such a glass as half-empty are pessimistic, because they are focusing on the half of the glass that contains worthless air. In this way, optimistic people see only the positive aspects of the situation, and pessimistic people see only the negative aspects. But is it really that simple?

In any case, traditionally minded pessimists might appreciate the Pessimist's Mug, which will tell you when it is half-empty.

An Alternative Perspective

So, why should the glass being half-empty be considered a bad thing? After all, if the glass is half-empty, logic dictates that it has been completely full before. Thus the individual holding the glass has already had a half pint of beer (for example), and should at this point be in a mellow state of mind, with the prospect of consuming yet another half pint. After that, the possibilities for happiness only increase. The individual can buy another drink without a problem or, even better, another drink could be offered by someone else.

Well, my answer has always been 'There's room for another in there'!
I love half empty glasses - enough inside you to feel mellow, and enough inside the glass to promise more good talk and good company for a while yet.

One question remains: Is a glass filled to half its capacity really a good thing? Such a glass doesn't seem to have the glorious past, nor the joyous future that could be associated with a half-emptied glass. A glass like this could exist because there is not enough liquid left to fill it completely. On the other hand, it could come about because the drinker has run out of money. In both cases, s/he might be happy to have at least half a glass. But then again, the knowledge of it being the last glass of the day might make our drinker a very depressed person indeed.

Last Orders

I have always had a deep mistrust of people who use this question to judge others. When they ask me if it's half full or half empty I use this response: 'Are you buying?'

As this entry shows, there are a number of ways of looking at the half-glass conundrum, and ample room for debate. One could of course put an immediate stop to the discussion by making sure the glass is completely empty and ordering a new drink. Cheers!

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¹ For the purposes of philosophical debate, it is normally assumed that the glass doesn't contain rat poison or something equally unpleasant.