Introduction
Probability theory is a branch of mathematics that deals with the study of random events and their outcomes. It is widely used across various fields such as finance, economics, engineering, and science to predict the likelihood of an event occurring in the future. However, there are certain situations where probability theory cannot be applied due to its limitations.

Example
One such example where probability theory cannot be applied is in the case of predicting the outcome of a human decision. For instance, consider the scenario of predicting the outcome of a presidential election. While probability theory can be used to estimate the chances of a candidate winning based on past voting patterns, it cannot fully account for the human element involved in the decision-making process.

Human Element
Human decision-making is influenced by a variety of factors such as emotions, biases, and personal beliefs, which are difficult to quantify and predict using mathematical models. Therefore, it is impossible to accurately predict the outcome of a presidential election based solely on probability theory.

Conclusion
In conclusion, probability theory is a powerful tool for predicting the likelihood of an event occurring in the future. However, its limitations must be acknowledged and understood to prevent erroneous predictions. The human element involved in decision-making makes it impossible to apply probability theory in certain situations, such as predicting the outcome of a presidential election.