The terms hard and soft were originally used to describe science fiction literature and an individual works focus on either the hard or soft sciences. Historically, the natural sciences like physics, chemistry, and mathematics were considered the hard sciences while the social sciences such as sociology, psychology, and philosophy were considered the soft sciences. In line with this, science fiction novels that explored more technical aspects of future invention were considered hard science fiction while stories that focused on the social aspects of life in the future were considered soft science fiction.

Worlds are like a good cheese: Sometimes soft, sometimes hard, and oftentimes better when aged.

More recently, worldbuilders have begun to use hard and soft to describe the level of detail found in any fictional world, not just science fiction ones. Those works that contain a great amount of explanation for how their worlds operate are considered hard, whereas those worlds that avoid going into such detail are thought of as soft. For an immediate example consider Tolkien’s Lord of the Rings (hard worldbuilding) versus Grimm’s fairy tales (soft worldbuilding). In hard worldbuilding, the systems that link elements together are well defined and follow a rigid logic understood by the audience. This means that things like the nature of magic and how it operates are fully defined and explained. There are well clarified rules governing fantastic elements. Perhaps spells need specific components to function or have certain limitations the audience understands. If there is a monarchy, often an entire family history is created, complete with characters perhaps never encountered within the story. In contrast, in soft worldbuilding the exact nature of how fantastic things work are nebulous, and not fully known to the audience (nor known to the author). Magic simply works because it is magic, there does not need to be any deeper explanation than that. Ogres are evil because they are ogres, there is no need to further explain their motivations. Faster-than-light travel just works, a quasi-scientific explanation for how it does is just clutter.

Note that the idea of hard versus soft worldbuilding is different than the idea of internal consistency. Both hard and soft worlds can be internally consistent, and audiences tend to value internal consistency far above experiencing either a hard or soft world (though even that can be a matter of personal preference).

Soft and hard worldbuilding exist on a spectrum, and different elements even within the same world can have different levels of ‘softness’ or ‘hardness’ to them. An author may design a robust system for how fairies evolved in their worlds, but the cosmic deities next door remain an utter mystery to everyone involved. Muddying the waters somewhat is that as a worldbuilder, you may not always show your audience your whole world. This may give the audience an impression of ‘softness’ when in reality your world is completely flushed out. Many worldbuilders build worlds with the intent of only showing their audiences 10% of it.

There are reasons to favor soft or hard worldbuilding. Soft worldbuilding lends itself to worlds where a sense of wonder or the preservation of the unknown is an important consideration. Perhaps there are things we as the audience just are not meant to know. The limits of a fantastic ability, the motivations or plans of a cosmic being, or the origins of a mysterious and predatory alien may be examples of elements best left mysterious. Often it is better to keep these elements soft, as it reinforces the idea that some things just cannot be comprehended. In addition, some things are just better left to the audiences’ imagination, as individuals will tend to create what they believe to be the best explanation for things. And oftentimes it simply is not necessary to the story. The Wizard of Oz does not explain how the Ruby Slippers work and why tapping your heels together is important, nor does it need to. Soft worldbuilding also frees the creator to explore more fantastic things without the need to explain their causes.

Hard worldbuilding lends itself to worlds that strive to feel more ‘real’ as the reasons why things are the way they are in this fictional world are readily apparent. A worldbuilder is transporting their audience to somewhere new, and each new detail about how this novel place operates can further the immersion and highlight the differences between that world and our own.

Over time worlds will tend to become harder as authors build off what has previously been established. This is especially true for works that exist as expanded universes. However, this can cause problems if new explanations for previously soft elements do not match with an audience’s preconceived, imagined expectations. Equally problematic is when a new explanation for a previously soft element creates internal inconsistencies.

PROS

• Allows builders to dive deep into their worlds and imagine how everything interacts
• Gives audiences explanations for truly alien or fantastic worlds
• Can aid in immersion

CONS

• Time consuming
• Can lead to unintended elements being incorporated
• The more elements that are incorporated the larger the chance for internal inconsistencies to arise

PROS

• Preserves a sense of wonder, otherworldliness or the unknown
• Allows audience to create/imagine their best version of things
• Allows worldbuilders to focus more on elements they want to explore and leave other elements soft they don’t want to tackle just yet

CONS

• Can leave audiences feeling unfulfilled, or with lingering questions
• Soft elements may more likely feel like a Deus Ex Machina