I wouldn't call him a pessimist either for the reasons you cited. But I think it's also an exaggeration to call him an optimist. You could call him cheerful though. Maybe other people have different definitions of optimism and pessimism than I do, but I would call it expecting good things to happen. Puddleglum expects bad things to happen, but he doesn't let his expectations keep him from doing what he believes is right/most practical under the circumstances. I'd describe him as "resourceful" or "uncomplaining" rather than "optimistic to the point of stubbornness."

I love that the character can't really be pigeonholed as an optimist or a pessimist. It's a good message about how complex people (or in this case, marshwiggles) can be.

Some people have a dark sense of humor, and that may be what Puddleglum is like. If you are little gloomy it doesn’t mean your a complete pessimist, but you just may have tendencies to look at life through dark colored glasses.  I think Puddleglum’s personality was like that. He was a little pessimistic but never to the point of despairing.  There are people in real life like that.  Didn’t Puddleglum say that the inhabitants of Underworld would teach you to take a serious view of life?  It was something like his view, but of course he was a Narnian created by Aslan so he was still cheerful even though he had a somewhat dark view of the world.

This article views Puddleglum as a cheerful pessimist:

https://narnia.fandom.com/wiki/Puddleglum

I think it is generally quite accurate and for the most part expresses my views.  I’m not sure if he could have been considered an alcoholic, although he was quite drunk during the time he spent with the giants.

  Simply put, he's a brick. A hardy, determined person who looks for disaster at every turn but braces himself with a positive thought and keeps pushing on. 

A pessimist sees the world in a shadow. An optimist sees the world through rose-colored glasses. Puddleglum sees the shadows and even looks for them, but he faces them down while looking on the bright side at the same time (even when that "bright side" runs along the lines of "at least being buried alive will save funeral expenses.") Yet he doesn't live as if bad things never happen.

He's not a pessimist in that he doesn't let the negative things dictate his behavior. As Col. Kink points out, He's not an optimist because he isn't oblivious to bad things or only ever expects good outcomes- far from it! He's more of a tough-as-nails realist. 

The best illustration of this is his attitude when the kids are doubtful about setting Rilian loose. He doesn't know what will happen. He even expects Rilian to kill them all. But he maintains that this doesn't let them off following the signs. 

A pessimist might have refused to release Rilian. An optimist would have assumed it would all turn out all right. Puddleglum does neither, and that sets him apart as a truly brave person.

While Puddleglum is an optimist, he is not the type of optimist you would expect. For example being optimistic means the opposite of being pessimistic. While Puddleglum tries to make the best of every situation, he doesn't make their current situation feel any better. If he was completely optimistic then whatever the problem is, he would think the exact opposite of that and give the feeling that they can get out of the problem, giving them hope that there is a solution. Whereas Puddleglum, finds a positive out of the negative situation. Not giving them a solution or hope of a solution even, but instead finding a benefit in the problem they have.

(@gp, I find it quite funny that you're defending Puddleglum so much. It's funny because I would do the exact same thing for Edmund. )

It may seem that Puddleglum is depressed at times, but looks can be deceiving. I think he's always alert whenever something is up- like if it is dealing with giants or mysterious nights or beautiful ladies.

@jasminetarkheena 

I always thought Puddleglum was a little smarter than Jill and Eustace in The Silver Chair. He was skeptical of The Lady of the Green Kirtle when the three of them met the Lady traveling with the knight, who was Prince Rilian under her enchantment. When I first read The Silver Chair I wondered why Jill and Eustace didn’t become suspicious of the Lady and her companion when they first met them in their travels. Puddleglum was immediately skeptical, which may appear pessimistic, but he realizes the truth early in the situation. 🙂

@narnian78 May have because they were children, and Puddleglum was "older and wiser".