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What is fuzzy logic in AI?

Fuzzy logic - the secret sauce for AI's warm and fuzzy feelings! All jokes aside, did you ever wonder if computers can navigate uncertainty and imprecision just like our human minds? I think we should find out.

17 August, 2023
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Fuzzy logic - the secret sauce for AI's warm and fuzzy feelings! All jokes aside, did you ever wonder if computers can navigate uncertainty and imprecision just like our human minds? With all the latest advances in AI technology, they surely can, right? Enter fuzzy logic – the enigmatic concept fueling such possibilities in artificial intelligence.

Continuing our recent installment of useful AI-related articles, which, for example, has a practical guide on how to integrate AI with existing systems, we decided to touch on such an interesting concept that still remains less known, even amidst the boom of AI and everything related to it. And if you’re ever planning on using AI development services, you need to know what it is.


Fuzzy logic defined

What was the perfect excuse for AI to say, "I'm not wrong; I'm just a little fuzzy!" has turned out to be an exciting step out of the usual ways of traditional logic, which has a tendency to classify information using binary distinctions like yes/no, true/false, or day/night.

In contrast, fuzzy logic takes a different approach by describing the middle ground that exists between these clear-cut black-and-white situations. It can be thought of as an expanded version of conventional (Boolean) logic, capable of encompassing the idea of partial truth - meaning truth values lie between "completely true" and "completely false."

In various organizations, numerous complex problems cannot be adequately addressed using straightforward yes/no or black/white programming responses. In such cases, solutions often lie in ambiguity, where fuzzy logic comes into play and proves valuable.

Fuzzy logic effectively deals with imprecision or uncertainty by assigning different degrees of credibility to propositions, allowing for a more nuanced and flexible approach to problem-solving.

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Comparison between fuzzy logic and traditional logic

The following are five factors that create the main differences between fuzzy logic and traditional logic.

Fuzzy logic operators

Traditional logic operates on binary principles, where statements are either true (1) or false (0) without any in-between values. It follows the principles of classical set theory and crisp boundaries, while fuzzy logic introduces a whole spectrum of truth values between 0 and 1, allowing for degrees of truth or membership. Its operators, such as AND, OR, and NOT, handle these fuzzy truth values, enabling AI systems to handle imprecise and uncertain data.

IF-THEN rules

In traditional logic, IF-THEN rules are based on exact conditions, making it rigid and less adaptable to real-world scenarios. It follows a precise cause-and-effect approach. IF-THEN rules in fuzzy logic can accommodate linguistic variables and approximate conditions. This flexibility allows for a more natural representation of human reasoning, considering shades of gray and enabling better decision-making in uncertain situations.


Defuzzification is not applicable in traditional logic, as it doesn't deal with fuzzy or continuous values. Its crisp nature leads to straightforward decision outputs. On the other hand, defuzzification is a crucial step in fuzzy logic, where fuzzy outputs are transformed into crisp values. This process converts the fuzzy membership degrees back into concrete actions or values, making it applicable in real-world control systems.

Applying truth values

Traditional logic adheres to the principle of the "law of excluded middle," meaning a statement is either true or false, with no intermediate values. Fuzzy logic, however, embraces the "law of non-excluded middle," allowing statements to hold partial truth, varying from completely true to completely false. This accommodates uncertainties and vague information, providing more nuanced reasoning capabilities.

Linguistic variables

Linguistic variables are a cornerstone of fuzzy logic, enabling AI systems to process human language and fuzzy concepts. It allows the integration of qualitative and quantitative data, bridging the gap between human and machine communication. Meanwhile, traditional logic operates with numeric variables and precise data, making it challenging to deal with linguistic concepts and human-like reasoning.

Fuzzy logic architecture

The fuzzy logic architecture has four main parts.

Fuzzy Logic Architecture
Fuzzy logic architecture

Rule base

This component contains a set of rules and IF-THEN conditions provided by experts to govern the decision-making process. These rules are based on linguistic information, and recent advancements in fuzzy theory have led to more effective methods for designing and optimizing fuzzy controllers. These developments often result in a reduction in the number of fuzzy rules, enhancing the system's efficiency.


The fuzzification stage is responsible for converting crisp inputs, which are precise measurements from sensors, into fuzzy sets. These crisp inputs typically represent parameters like temperature, pressure, or RPM (revolutions per minute) that are used as inputs to the control system for further processing.

Inference engine

The inference engine evaluates the degree of matching between the current fuzzy input and each rule in the rule base. It then decides which rules should be activated based on the input. Afterward, the activated rules are combined to generate appropriate control actions.


Defuzzification is the final step, where the fuzzy sets obtained from the inference engine are transformed back into crisp values. Several defuzzification methods are available, and the choice of the best-suited method depends on the specific expert system, aiming to minimize error and provide a precise output.


Benefits of fuzzy logic in AI

Unlike traditional binary cases of truth, fuzzy logic encompasses not only the extreme cases of truth represented by 0 and 1 but also includes a range of intermediate degrees of truth. This allows AI systems to handle nuanced and imprecise information, making them more capable of emulating human-like decision-making processes that often involve shades of certainty and uncertainty.

In general, the benefits of fuzzy logic in AI include:

  • Simple and understandable structures. Fuzzy logic systems have an easy-to-understand structure, making them accessible for implementation and interpretation.
  • Control of machines and consumer products. Fuzzy logic enables the control of machines and consumer products, providing adaptable and responsive systems.
  • Dealing with engineering uncertainty. Fuzzy logic proves beneficial in engineering, where dealing with uncertainty is common, allowing for more robust decision-making.
  • Robustness with inexact inputs. Fuzzy logic systems remain mostly robust even with imprecise or approximate inputs, reducing the need for precise data.
  • Handling feedback sensor issues. In situations where feedback sensors malfunction, fuzzy logic can be programmed to adapt and continue functioning.
  • Easy modification for improved performance. Fuzzy logic systems can be easily modified to enhance or alter system performance, enabling quick adjustments to changing requirements.
  • Cost and complexity efficiency. The use of inexpensive sensors in fuzzy logic systems helps maintain low overall system costs and complexity, making it a cost-effective solution for various applications.

Drawbacks of fuzzy logic in AI

Fuzzy logic does come with some drawbacks as well:

  • Limited accuracy. Fuzzy logic may not always produce highly accurate results, as they are based on assumptions and may not be universally accepted.
  • Inability to recognize complex patterns. Fuzzy logic may not be well-suited for recognizing intricate patterns seen in machine learning and neural network models.
  • Extensive testing for validation. The process of validating and verifying a fuzzy knowledge-based system requires extensive testing with hardware, which can be time-consuming and resource-intensive.
  • Difficulty in defining rules and membership functions. Setting precise and appropriate fuzzy rules and membership functions can be challenging, as it requires expertise and a deep understanding of the domain.

Despite these disadvantages, fuzzy logic remains a valuable tool in various applications where dealing with uncertainties, and imprecise data is crucial for decision-making and control systems. Let’s discuss those applications now.



IBM's Watson supercomputer stands out as one of the most notable examples showcasing the utilization of various forms of fuzzy logic and fuzzy semantics. Some of the best healthcare-related and industrial applications of fuzzy logic include the following.


Fuzzy logic plays a crucial role in medicine, facilitating improved patient care and diagnosis. It aids in controlling arterial pressure during anesthesia administration, ensuring patient stability and safety.

In diagnostic radiology and support systems, fuzzy logic assists in accurate medical diagnoses by analyzing images and patient data, offering a nuanced interpretation. It proves valuable in diagnosing conditions like prostate cancer and diabetes, combining multiple variables to assess likelihood.

In diabetes management, fuzzy logic helps determine disease severity and progression, enabling better treatment planning. Its ability to handle uncertainty and vagueness in medical data enhances decision-making and contributes to better patient outcomes.


There are TONS of fuzzy logic applications in various industrial fields. Here are some of them:

  • In the automotive industry (Honda, Nissan), fuzzy logic is employed for gear selection, considering factors like engine load, road conditions, and driving style to optimize performance.
  • Dishwashers (Matsushita) utilize fuzzy logic to determine the washing strategy and power required, taking into account the number of dishes and the level of food residue for efficient cleaning.
  • Environmental control systems, like air conditioners and heaters, utilize fuzzy logic to adjust output based on factors such as current and target temperatures, optimizing comfort and energy efficiency.
  • In aerospace, fuzzy logic plays a vital role in managing altitude control for satellites and spacecraft, taking environmental factors into consideration.
  • Copy machines (Canon) leverage fuzzy logic to adjust drum voltage based on factors such as humidity, picture density, and temperature, ensuring high-quality outputs.

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Overall, fuzzy logic bridges the gap between rigid binary logic and the nuanced complexities of human reasoning. By allowing intermediate degrees of truth and handling uncertainty, it allows AI systems to make more human-like decisions.

Despite its quirks, fuzzy logic proves to be a powerful tool in various applications. From medical diagnosis and patient care to optimizing industrial processes, fuzzy logic shows its adaptability and versatility. It enables machines to understand linguistic concepts, handle imprecise data, and provide robust and responsive control.

So, next time you encounter a machine making a "fuzzy" decision, just remember that it's embracing its human side and doing its best to find the perfect balance in a world of shades of gray!

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