Is there such thing as "luck" in chess?

Being tired is not random (it's a predictable consequence) but its effect is random.

Calling it lack of focus is nonsense.

Very true, demonstrating that life is very different from a math test.

Well practically speaking how ridiculous that is we wouldnt need to continue, but let's think about it logically.

It cannot be only skill. If skill was the only factor, the following would always be true:

The higher level of applied skill, the better the outcome. As examples have shown, this is not the case. So you don't call it luck, what is the missing factor here?

Seems people are using their own definition of luck. Before discussing whether chess has luck people should agree on what luck means.

We can't reliably quantify the strength of a move even after the move is made... so certainly the course of a game has some randomness to it.

I was playing online blitz recently.

I clicked on the bishop that I wanted to move. I clicked on the square I wanted it to land on.

Then I waited a split second. My computer lagged during that moment. When the lag resolved itself, I saw that my bishop had ended up one square short of the square I had clicked on.

That simply left my bishop hanging, through no action of my own. It was a computer error. (Or connection error, I don't know the technicalities of it.)

Either way, it gave my opponent a free bishop, which they gratefully accepted. The game was soon over after that.

Bad luck for me. Good luck for them.

I shrugged and moved on, because I know that such luck is part of the game. Sometimes the luck goes your way. Sometimes it goes the opposite.

A couple of observations:

     There is a significant difference between playing chess and solving complex math problems--in math there is no one changing the parameters of the problem to make it more difficult after each step you take in solving it.

     There may be no random element designed into the play of the game, but it is played in the material world by actual humans, so twists of fate can upset the best laid plans. Computer glitches or electrical blackouts in online competition, heart attacks or doctors called away to an emergency during a otb game are instances of games won/lost with no influence of the players' skill.

     Even the greatest players make occasional gross blunders. While such failures can be cited as the losing player's own lapse, the recipient of such largesse--an event both players know would happen once in 100 similar situations--will consider themselves lucky that they were the one sitting across the board at that rare moment.

     But there will be those who maintain that studying the game and improving your knowledge was simply increasing your skill. Had you looked at that line six months earlier because you wanted to try a new defense and recalled it when you saw it over the board, would that still be called luck?

I believe there is no wrong side to this debate, people just love to argue with each other.

The game of chess was created with no luck or random chance element built into it (this is fact), however, a player can still get lucky by choosing the best move in a random position (also fact). 

     Just another example of what makes chess such a fascinating avocation and this discussion of luck go on for so long. As the key concept is unquantifiable and lacks material existence it can be looked at in many ways and there are many ideas about how and how much it may enter into chess.

     Sometimes a situation will arise at the board and I'll see a position that seems familiar. While pondering the possibilities I'll suddenly remember that I studied that line once but all I can remember is the next move or two and the long-range aim. I will usually plunge ahead on the theory that I decided before what the best move would be, so I ought to trust my own judgement. Sometimes as play goes on the ideas return to me, sometimes I can't remember what to do and fumble, sometimes my opponent may see the looming trouble and take evasive action that turns out to be worse than the book line. Of course I can go astray there too. 

     Is my remembering the line good luck for me? Was it bad luck for my opponent to choose a line to which I knew the refutation? Was it lucky for my opponent that I couldn't remember the moves correctly? Was luck involved at all?

     The fact that there is no definitive answer makes for a many-faceted discussion and keeps this forum interesting.

Which is why I suggested the conversation move from if there is luck in chess, to how much is there. Because, for all practical purposes, the first question has been answered. 

Whatever you need to believe to prop up your notion that you are the world's best debater .

Really?  That's amazing!  So I might find a winning lottery ticket because I am tired?  Can I grow a third arm because I am tired?  Or maybe being tired has a limited set of reasonably predictable consequences, which makes doing things while you are tired a poor use of your skills and experience.

Since everyone is saying "poor play by the opponent is NOT luck, just rather lack of skill" I have an example meets the requirement where the opponent did nothing wrong:

When a blunder turns out to actually be a brilliant move by accident, that's an example of luck.

I recall a video where Daniel Naroditsky thought he messed up by mouse-slipping, but realized that his mouseslip turned out to be a brilliant sacrifice move, then won a few moves later.

That's luck because when you mess up, that's supposed to hurt you, yet in this case, it helps you.

Why do you define skill as an absolute?  It is not.  The "missing factor" is that you don't understand that comparing two people's skills is not a comparison of discrete values (I assume you are going by rating, but of course ratings are defined as probabilities for win/loss ratio between opponents, so that's not correct).  You might as well compare two sine waves, one with a higher base Y value than the other, and then make some claim about how one wave should always have a higher Y value at every point on both sine waves.

As any game, sure there is

...so is this what passes for a good argument in your circles?

Learn the lesson.  Hypocrisy always catches you out. 

Coolout and I disagree on whether there is luck in chess, and in sports in general, so your premise is busted right out of the gate.  

Incorrect.  Chess is a game of perfect knowledge.  Not being to perceive, understand or interpret an outcome is not the same as that outcome being random.  The entire universe trundles along without human beings being aware of 99.99% of it, and the universe is not driven by luck...or perhaps for some posters here, it is.

Mouseslips are not part of the game of chess.  You can say that Naroditsky got lucky, but not that this proves there is luck inherent to the game of chess.

This discussion would have been over a long time ago if the title were simply "Do you think there is luck?"...it's the "in chess" that makes this discussion go.

You're slipping.  Coolout has stated incessantly that he does not consider the selection of colors to be luck.  The problem with arguing with you is that a week or two later, you have forgotten most of what went on...