Just to keep everyone in the loop, I'll explain again that a heuristic is a guideline. This is at least one thing I will give to Gygax: he understood that, in many cases, the game's open perspective on human behavior and choice would produce circumstances that could not be predicted and for which rules could not be effectively invented. In the moment, at the time of a player's innovation, the DM would be compelled to think heuristically, to go with a gut instinct and make a ruling that would fit the situation. (It's hoped that, once this ruling is made, that it sets a precedent for further like circumstances that occur later in the campaign, but that is another post that I've already written).
In many situations, however, the very nature of the DM defies the possibility of creating a rule at all - because, of all things, the game demands flexibility. It is here in particular that the use of a heuristic is a great benefit to a DM. I'll give an example.
Usually, when I wake up in the morning, I have a cup of coffee. This is true in about 19 cases out of 20. I like coffee and when my world is working properly, I'm able to make coffee happen one way or the other. However, I am not like these people who say, "I cannot function without a cup of coffee." Coffee, for me, isn't a "rule." I can do without it just fine. Sometimes I don't have time to obtain coffee, sometimes I'm sick with a flu or cold and I would prefer tea, sometimes I get distracted. Coffee isn't necessary, it is a choice - and the fact that I tend to make it often doesn't eliminate the heuristic decision that I make about it each day.
I will give another example. When considering how many monsters to throw at a party for a given encounter, I'm not bound by any rule that says I must make the encounter "balanced." Not all situations that I expect the party to face will be balanced. Sometimes the party will outnumber their enemy; sometimes the enemy will outnumber the party. The decision that I make in choosing a number of monsters is heuristic; I'm not bound by any rule in the game that I know of. I am, however, bound by my experience and judgement to enable the party to assess the encounter in some way that gives them an option to survival. Thus, I would not create a situation where the monsters appeared immediately next to the party, out of the blue, without any suggestion that the party was in a dangerous place, with the monsters getting first action and then pounding the players into dust. That would be a BAD decision on my part and I wouldn't make it.
Presuming that someone will think of or suggest a situation where an assassin might do that to a specific party member, I will venture forth to say that this has happened twice in all my campaigns in the thirty-seven years of my experience. In the first instance, the assassin missed the kill and the player defended himself justly. In the second case, the assassin was the player's own assassin henchman, abandoned after dying, left unburied, only to rise as a revenant and successfully kill the PC. It was agreed by all present, including the victim, that the murder was understandable.
So I am saying, in choosing what sort of encounter the party occurs, I make a decision that may inordinately threaten the party but will not betray the party's trust in me, their DM. I curb any sense of entitlement on my part regarding what sort of encounter is imaginably possible and choose instead an encounter that will make a good game. When I make this decision in the moment, the decision is heuristic; the making of a heuristic decision saves time and enables me to tailor my game to the specific moment in time that the game is being played. This is what I mean by "flexibility."
When DMs talk of "winging it," this is what they mean - though of course they don't give it a label, calling it heuristic, unless they also happen to work in the field of psychology or a related subject. Most who claim to DM this way express how it works without knowing precisely why it works . . . I am hoping with this post to give them a clue as to what sort of reading they might want to do if they'd like an intellectual handle on what they're doing.
There are many other DMs who feel very uncomfortable with heuristic decisions, who want every part of an adventure to be measured out and predetermined, expecting that this will ensure a positive shape to their games ~ and often it will, though there are no guarantees. This measuring is, for some, the result of a fear that making a heuristic decision during the campaign will result in some terrible mistake that hurts that night's experience for the players or ~ even worse ~ challenges the viability of the whole campaign.
(yes, it is excessively dramatized, but I've heard and read people expressing exactly this fear)
Designing everything in advance is, however, an onerous process that often suspends game play for weeks while the DM gets things ready. As well, playing with everything prepared lacks the flexibility of a heuristic. While I can decide in my campaign that the players need a shot in the arm to get them pumped up, creating a brief combat for that purpose, the DM with the prepared, dovetailed adventure may have no such opportunity without compromising the adventure's structure. As a result, on a given night a prepared campaign can fail to hit emotionally and the party is left slogging in dull misery for hours without respite.
It is then assumed that the fault lies in the ability of the designer and not in the functionality of the design. As such, DMs rush off to pay a lot of money for a "professional's design," a store-bought module, that will often unfortunately produce the same sour experience (then causing the DM to assume that it is a personal failing and that nothing whatsoever can be done, therefore it is time to quit).
We must understand that the risk of the prepared structure is that it isn't flexible. It is like deciding that on June 28, 2018, we will get in the car, come hell or high water, drive to the beach and ~ by sweet cheese and crackers ~ have a good time. And if the weather is bad, Jack's mother has just died or Mary has broken her leg, tough tookies: we're going. For reasons having nothing to do with the quality of the adventure or the quality of the DM running the adventure, a prepared adventure can play brilliantly with one group of players on a Tuesday and tank the following Friday. There are a hundred reasons why this can happen.
Desirably, we should be creating adventures that have the virtue of preparedness AND the virtue of opportunity where it comes to make a heuristic decision. Neither approach, to be sure, will work optimally by itself, whatever an individual DM might claim. We need to use all the resources at our disposal if we want out games to be better suited to our players.
Now, I will try to drag this around with my next post to the original points I made about decision-making and introspection. Wish me luck.