Mack is the acknowledged leader of a group of bums who live at the Palace Flophouse and Grill. All we know about him before he moved to Cannery Row is that he had a wife, but things didn't work out with her. Nowadays he spends his time enjoying life: drinking "punch" or whiskey over at the Palace and looking for ways to make a little money without working too hard.
So, are we talking hidden depths? Or is this one guy whose life is all on the surface?
It's kind of surprising that Mack is such a leader, because everyone seems a little nervous around him. Even Doc "look[s] up a little nervously as Mack enter[s]" (9.16).
See, Mack never stops by just to say hi and hang out. He always wants something and will try to get it without the other person even realizing they've given something. Like when he convinces Lee Chong that the boys will be doing him a favor by living in the vacant building.
Or when, after Doc gives him a note for gas money, Mack wracks his brain to find a way to get some cash out of the deal. First he tries to get the guy at the gas station to give him some cash instead of all the gas, and then he tries to get some of that gas in a canister so they can sell it. (Luckily, Doc is one step ahead of the game, and had cleared it all with Red Williams the night before.)
Or when, on their frog-catching field trip, Mack gets the captain to go from kicking Mack and the boys off his land at gunpoint to offering them whiskey and frogs up at his place. That little exchange goes so well that, by the end of the night, the captain "felt it was an honor to have them burn his house clear down, if they wanted to" (15.22).
If there's more to Mack than a slick con artist, Doc helps him see it. What Mack wants even more than whiskey—okay, maybe not more than whiskey—is to do something nice for Doc. See, Mack's a little bothered by the fact that, when he wants to be generous, he always ends up benefiting in some way: "I'd just like to give him something when I didn't get most of it back" (13.32).
Hm, giving things away without asking anything in return? Sounds a lot like Doc to us.
Like we said, Mack isn't just a con artist. According to Doc, he's an artist of life.
Mack just isn't impressed by money, so he doesn't see the need to cramp his style by trying to make a lot of it or hoard it up. Result? He's truly happy. Doc says that "in a time when people tear themselves to pieces with ambition and nervousness and covetousness, [Mack and the boys] are relaxed" (23.11). Instead of killing themselves trying to make enough dough for, say, indoor plumbing, Mack and the boys just wash their faces in a bucket and feel good about it.
The way Doc sees it, this "true philosoph[y]" makes up for all Mack's conning (23.11). Us? We're not so sure. Let's keep looking.
The narrator sure seems to like Mack and the boys. He calls them "the Virtues, the Graces, the Beauties" of Monterey, and they do seem to be a little like deities (2.2). Their fate is tied to the Row: after they mess up Doc's first party and become "social outcasts" (23.6), everyone else in Cannery Row suffers too: "It was a bad time. Evil stalked darkly in the vacant lot. [ . . . ] Mack and the boys seemed to be the node of trouble" (23.29).
But when they're happy, everyone else is happy too. After Mack and the boys decide to throw the second party, "the benignant influence crept like gas through the Row. [ . . . ] Triangulation might possibly have located [the source of it] in the Palace Flophouse and Grill" (25.5). Just like the way things go badly down on Earth when there's trouble up at Mount Olympus, Mack and the boys seem to have some kind of paranormal effect on the rest of the Row.
And this is weird, because you'd think that these guys, who don't have a steady job between them, would be the least important people on the Row. Everyone else we meet is gainfully employed (more or less). Dora's a madam, Lee Chong is a grocer, Mr. Malloy is, uh, a landlord. Mack and the boys can't really support themselves without help from the others, yet they're the most important guys on the block.
Here's what we think: Steinbeck is trying to tell us something about debt. The most important people in town aren't the creditors, they're the debtors. Without the debts that tie people to one another, there wouldn't be a community at all.
Cannery Row doesn't end like the Cosby Show, with the Golden Moment of everyone learning a valuable lesson. But Mack does seem to learn something: he figures out how to do something nice for somebody without it only benefitting him.
Okay, let's look at the first party: here, Mack's big idea is to get Doc to fund his own party, since Doc's going to pay for the frogs Mack and the boys collect. Of course, everything blows up in his face. The party is fun while it lasts, but he ends up owing Lee Chong a ton of money, Doc's lab is trashed, and everyone in Cannery Row basically hates them.
For the second party, Mack gets everyone in Cannery Row in on the party planning:
The knowledge or conviction about the party for Doc was no sudden thing. It did not burst out full blown. People knew about it but let it grow gradually like a pupa in the cocoons of their imaginations.
Mack was realistic about it. "Last time we forced her," he told the boys. "You can't never give a good party that way. You got to let her creep up on you" (25.8-25.9)
This time, the whole town puts the party together. Everyone has a stake in making sure the celebration goes off just right—even Doc. So what does Mack learn? He learns that you can't throw a real party for someone if in the end it's only going to benefit you. And he learns that the whole community together can pull something off that Mack and the boys couldn't do on their own.
Hm. Maybe this is a Valuable Lesson, after all.