Intuitive Rationality: simulating Sherlock with Intuitive General Intelligence


The last decade has seen a much greater interest and understanding in how people really think. The research and ideas, well represented in Daniel Kahneman’s excellent book Thinking, Fast and Slow have shown what has been known for hundreds of years, that humans are not entirely rational but instead are influenced by several factors in arriving at decisions, like subconscious and environmental processes, and a need for emotional comfort and ideological consistency.

While these notions are not new, they have appeared in a new context, the 21st century where technology looms large and social connection has never been greater. These contemporary processes mean that the various ways that people think have never been more important. Understanding cognitive biases is now critical for anyone in being more aware and efficient in not just their own thinking but also that of others.  

Unbridled and pure rationality, devoid of the heuristic influences, is not a practical or even possible for human beings. 

As Falk et al., 2017  write…

“The number of computations required for exact logical or probabilistic reasoning grows exponentially with the number of facts and variables to be considered. As a result, to exactly and completely reason through just a single complex everyday situation involving hundreds of variables could require more computations than can be performed in a human lifetime (Van Rooij, 2008). Thus, if a person were to reason out everything strictly according to the laws of logic and probability theory she might die before she reached her first conclusion.” 

Thus there is a practical need to depart from pure rationality and combine it with other processes to be effective. There is a need to simplify – and significantly shorten the time involved – the thinking process. That essential need is now being explored in the fields of psychology, neuroscience and behavioral economics. 

This pursuit of a full understanding of how the human mind tries to marry rationality with heuristic, subconscious processes is also very relevant to one other area, one that is critical for human decision-making – prediction.  Many people have been associated with the quote, “prediction is easy unless it’s about the future.” It’s probably Danish in origin but universally accepted. 

For many years, especially with the advent of fast processing, data analysis, including prediction, was based on pursuing the purely rational. After all, computers had not only vast processing power but much more time on their hands than the average human. With such fast processing, it was now possible to stick to the facts, and just the facts, and  rid ourselves of all the shortcuts necessary for human beings.

And for the most part that has been the direction of predictive science. For the most part. But there was at least one person who saw the rise in technology, processing speed and accuracy, as a way to try to simulate human-decision-making, not purely rational processing. Such a system would more likely reflect how humans think and given that many predictions and analyses are actually about human behavior, the system might prove more accurate than purely rational-based predictions.

Grant Renier, started his venture into ‘Intuitive rationality’ 30 years before Nobel Prize winner Daniel Kahneman published his ground-breaking book. Grant designed his system to  incorporate the various biases and heuristics that humans use in decision-making, thus simulating human decision-making not pure rationality.

With decades of data, Renier’s Intuitive Rationality system has performed extremely well, outperforming most other predictive analysis systems in many different areas: the financial market, sports, elections, medicine, etc.  Grant and his principle technologists have translated the core logic to their commerical version called IntualityAI. 

Which biases and heuristics are programmed into IntualityAI and how are they incorporated? This book answers those questions, as well as demonstrating the proven success of such a system. 

We have tried to make the book readable and entertaining. The first part of each chapter is about a specific bias or heuristic that is incorporated into IntualityAI’s predictive analysis. The second part is how that is actually achieved within the system.  

The use of Sherlock Holmes stories is testimony to the fact that the fictional detective was well aware of cognitive biases and rational thought and provides a good demonstration of how they work – or don’t work — in real life, detective work. 

Howard Rankin

Grant Renier


The book will be completed for distribution in 2021.


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