How does the Model Penal Code classify states of mind in criminal cases?

The Model Penal Code clarifies the concept of mens rea—or the "guilty mind"—by reducing the variety of mental states to four distinct categories. These classifications are used to determine criminal liability in law:12

• Purposely: The actor has an actual, consciously formed intent to achieve the criminal result.2
• Knowingly: The actor has a conscious awareness that their conduct will produce the criminal consequence.2
• Recklessly: The actor consciously disregards a substantial and unjustifiable risk that their conduct creates an unreasonable peril.12
• Negligently: The actor is inadvertent to a risk that would have been apparent to a reasonable person.2

While most crimes require a showing of acting purposely, knowingly, or recklessly, negligent conduct generally only supports a conviction if the specific definition of the crime includes it. These classifications have been widely adopted by U.S. states to rationalize the mental element of criminal offenses.1