What's alignment? Does it mean anything in 5e?

My first exposure to the D&D alignment system was in old DOS games where you could pick your alignments from what looked to me like a jumble of words like "good" and "chaotic." I didn't understand what any of the terms meant, and they all looked like "chaotic true neutral good" to me. Now, of course, I understand that an alignment like that is impossible on the good-evil, lawful-chaotic axes, and I promise I'm rolling my eyes at my younger self just as hard as you are.

Hillsfar was my favorite of the few old SSI games we had, because it was basically a burglary simulator. Yes, it also had an archery simulator and an arena simulator and a brute-force-password-cracker simulator (because your older siblings lost the copy-protection code wheel years ago), but the best things to do involved breaking into buildings and looting them. Even if you liked fighting in the arena, you could loot buildings until you were caught and thrown in the arena. Then you'd just bludgeon some poor minotaur unconscious with a stick and walk out a free elf, ready to continue your crime spree.

But for all alignment mattered in those old Strategic Simulations, Inc. games, they may as well have been nonsensical word salad like evil-agnostic-neutral-good. Sure, some classes had to be certain alignments during character creation, but past that, it didn't seem to matter if your lawful good cleric tried to rob and murder.

Alignment: A 2-axis morality graph

If you'd like to make sense of alignment, you need to understand that it's where a character falls on two axes: The good/evil axis and the lawful/chaotic axis. If you try to help other people, you're good. If you exploit the suffering of others to further your own ends, you're evil. If you stick to a set of rules and like authority, you're lawful. If you don't like authority and you favor spontaneous action, you're chaotic. These two axes are independent of each other — being lawful doesn't make you good, and being chaotic doesn't make you evil. Add neutral as a center point on both axes, and you've got the nine alignments.

5e paladins≠lawful good

Before 4th Edition, alignment was a mechanic in D&D. Players were still encouraged to act as they saw fit, but actions too many or too far outside a character's alignment would prompt the DM to change a player's alignment — and that came with serious consequences. The AD&D Dungeon Master's Guide explains:

Changing of alignment is a serious matter, although some players would have their characters change alignment as often as they change socks. Not so!

First, change of alignment for clerics can be very serious, as it might cause a change of deity. (See DAY-TO-DAY ACQUISITION OF CLERIC SPELLS.) If a druid changes his or her alignment — that is, becomes other than neutral — then he or she is no longer a druid at all! Change of alignment will have an adverse effect on any class of character if he or she is above the 2nd level.

More specifically, that "adverse effect" was that the character would lose a level. They'd drop in XP all the way to the bottom of the level below their current one.

Beyond that, certain classes were restricted to certain alignments. Druids could only be neutral on the good/evil axis and monks could only be lawful. The strongest relationship between an alignment and a class is that paladins were originally required to be lawful good. If a paladin were to commit evil or chaotic acts, the dungeon master could strip the character of all paladin abilities except skills.

Third Edition relaxed alignment rules, and Fourth Edition de-emphasized them so completely that it ditched four alignments. Characters could be lawful good, good, neutral, evil or chaotic evil. Fifth Edition brought back the nine-alignment grid, but it didn't really reinstate alignment as a mechanic. It's almost entirely a tool for worldbuilding and roleplaying.
In a Sage Advice column (er … collection of tweets?), Mike Mearls explains: "Alignment in 5e describes things but does not define them. A fallen paladin = breaking an oath, not alignment."

There are a few items in 5e, like the Talisman of Pure Good and the Talisman of Ultimate Evil, which use alignment as a mechanic. But by and large, it's not used outside of roleplaying and worldbuilding.

Alignment is poorly defined

So in 5e, players aren't really punished for changing alignment. Many DMs will advocate ditching alignment altogether. But sometimes players and DMs still fall into the trap of thinking, "This character is lawful good, so she does this."
The problem with that, though, is that alignment shouldn't dictate your actions. It may describe your character in broad terms, but it doesn't define them.

If you try to use alignment to determine what your character will do next, you're going to run into trouble sooner or later, because the alignment system is incredibly vague. You can't act exactly like a lawful good character, because there are more than nine types of people in the world. If alignment was really an effective way to describe people's morality, every Intro to Philosophy class would have a chapter on Gary Gygax.

Not to keep returning to the What-Alignment-Is-Batman well, but it's such an entertaining debate because there are so many different incarnations of Batman that trying to nail down what defines him is like trying to hang a poster while standing on a swivel chair. Add the inherent wobblyness of the alignment system itself, and that makes trying to determine Batman's alignment also like trying to hang a poster while standing on a swivel chair, but only this time the wall is standing on a swivel chair, too. Spend too long in the endeavor, and you're likely to wind up on your ass, saying "Now that I think about it, he's definitely neutral evil."

He's lawful good because he helps others and he unwaveringly follows a personal moral code. He's chaotic good because he helps people but he willfully breaks the law and dodges the cops to do so. He's lawful evil sometimes because even though he has strict criteria for choosing his targets, he's become so absorbed by his quest for vengeance that he cares more about hurting bad people than helping good people.

If I were DM for whatever combination of Bob Kane and Bill Finger really deserves credit for the creation for Batman, I'd tell them to just write "neutral" on the character sheet and keep trucking.

Part of the reason that it's hard to define alignments is that the law/chaos axis has had at least two distinct definitions. It can refer to social conduct, where lawful characters respect rules and authority, or it can refer to personal conduct, where lawful characters are responsible and disciplined. In the original D&D rules, the good/evil axis didn't even exist, and lawful became a sort of shorthand for good and a lot of the time chaotic meant evil.

So what's it good for?

So far, I've said some pretty dismissive things about alignment. But truth is, I think it can be an incredibly useful tool. While it's not very useful for describing complex characters, it's great at giving players at-a-glance info and first impressions about:

• Creatures: Every 5e stat block for every creature includes alignment (Creatures that aren't capable of rational thought are "unaligned," but their stat block still includes an alignment slot.). This gives DMs a rough idea of how different creatures work together, and it gives adventurers who learn the creatures' alignments insight into whether they can avoid a fight, among other things. For example, you might be more likely to interrogate a lawful evil creature than a chaotic one, reasoning that lawful creatures are more likely to be working in groups and therefore may know more about your enemies' motives.
• Planes and pantheons: Most deities have alignments, and many of the common D&D pantheons have one main deity for each alignment, so knowing your character's alignment can help describe which gods they may serve or favor. Likewise, the outer planes of Great Wheel cosmology, sometimes referred to as "the homes of the gods," are divided up by alignment. This gives players with alignments a rough idea of how comfortable they'd be in each plane. As for DMs, making a pantheon or plane system using the alignment grid is a drop-dead simple way to get a respectable variety and ensure that you can tell stories with conflict between the planes and gods.
• Potential conflict: Good vs evil is a theme in many D&D adventures. Law vs chaos can also be a good conflict to explore thematically. But even in worlds where battle lines aren't so clearly drawn, characters that differ too widely in alignment are more likely to clash with one another.
• Characters' relationships with communities: 5e race descriptions will often include a race's tendency toward certain alignments. The Player's Handbook explains that while player alignment is never restricted by race in 5e, knowing your character's alignment and your race's alignment tendencies can be helpful from a storytelling perspective: "considering why your dwarf is chaotic, for example, in defiance of lawful dwarf society can help you better define your character." (PHB 17)
• Memes: Understanding any of the 5,000 alignment memes you see floating around.