21. Fill the gap This principle of logic states that, if all other aspects are equal the simplest theory is preferred over other theories involving additional factors.This is also called __

## Step 1<br />The problem is asking us to identify a principle of logic that states that, if all other aspects are equal, the simplest theory is preferred over other theories involving additional factors. This principle is also known as Occam's Razor.<br /><br />## Step 2<br />Occam's Razor is a principle that suggests that the simplest explanation or theory is usually the best one. This principle is named after the 14th-century English logician and Franciscan friar William of Ockham.<br /><br />## Step 3<br />The principle of Occam's Razor is used in various fields such as philosophy, science, and engineering. It is a heuristic that guides scientists and philosophers to avoid unnecessary assumptions and to focus on the most straightforward explanation.