# Difference between Effect, Principle, Theorem, Law, Theory and Hypothesis

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I work with design and we hear a lot a bout Fitts or Hicks Law, but then theres also things like Jakobs law (which seems to have no mathematical equation nor data, but seems logical) and Caroline’s Law (which I’ve only ever seen referenced but never saw the actual description) and Gestalt Principles. So I wonder if this is an in-field thing, if some are being erroneously used or am I just dumb xP Reposted cause it seemed previous answers were old and specific to mathematics

In: Other

Effect: This is an observed outcome or result that occurs due to a specific cause. For example, in design, the “halo effect” refers to the tendency of people to have an overall impression of something or someone based on one positive trait.

Principle: A principle is a fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning. In design, the Gestalt principles (like proximity, similarity, continuation) help explain how we perceive visual elements as grouped or separate.

Theorem: In mathematics, a theorem is a statement that has been proven on the basis of previously established statements, such as other theorems, and generally accepted statements, like axioms. It’s less commonly used directly in design but is more about the underlying math or logic that can inform design concepts.

Law: A law describes an observable phenomenon that always occurs under certain conditions. In design, Fitts’ Law, for example, predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target.

Theory: A theory is a well-substantiated explanation acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation. Theories may not be as commonly directly referenced in design, but they underpin many of the psychological understandings of how people interact with interfaces.

Hypothesis: A hypothesis is a proposed explanation for a phenomenon, made as a starting point for further investigation. It’s a testable prediction, often formulated as an if-then statement.

In fields like design, these terms can sometimes be used a bit loosely. Jakob’s Law, for instance, might not be a “law” in the scientific sense but is an observed and generally accepted pattern about user experience, stating that users spend most of their time on other sites; thus, they prefer your site to work the same way as all the others they already know.

Caroline’s Law, which you mentioned not finding much about, might be a less formal or less scientifically established concept, potentially more of a guideline or rule of thumb based on observations within the community.

It’s not unusual for terms like these to be adapted or used in different ways across various fields, including design. So you’re definitely not alone in feeling a bit mixed up by how these terms are thrown around!