As historians are quick to point out, the parallels between modern times and the classical world – including not only Greece, but also Rome – are plentiful. No new thinking here. In profound ways, our modern society, laws, forms of government and language are embedded in the classic traditions.

But there’s more to the story than that.

The history of philosophy, more broadly framed as the history ideas, tells a compelling story about a journey to new levels of understanding – a tale that traces evolution of ‘critical thinking’ itself.

At its core, philosophy is about learning how we ‘know’ what we know, and learning what we can do with the knowledge that can be gained.

Critical thinking and philosophy seem to share a common heritage, as shown in this table:

There is scant space here to do justice to such a rich history, but to advance the topic as part of my critical thinking series we need to at least expose the biggest pillars. In the paragraphs below, I focus on philosophers who have provided significant contributions to what has evolved as the modern notion of critical thinking.

1. Pythagoras. A pioneer in math, Pythagoras advanced geometry with his famous theorem on triangles. In so doing, he brought the concept of ‘abstraction’ into the mainstream. He effectively demonstrated that what we observe is one thing, while what we comprehend mentally is quite another.
2. Socrates. Famous for asking deeper and deeper questions to get to the core of an issue, Socrates was a relentless advocate of critical thinking. He is said to have used Pythagorean triangles drawn in the sand to challenge skeptics on their limited view of the ‘knowable’.
3. Plato. While famous as both student and scribe of Socrates and an early political scientist, Plato was important in this discussion for driving concepts of perfected universals – truth, as one example – derived from accepted perfections in abstract mathematics. When we think about ideal solutions and archetypes, we owe a debt to Plato for asserting their importance, laying ground work for the modern framing of ‘paradigm’ (Kuhn) and ‘mental model’ (Senge).
4. Aristotle. A critical inflection point in Western philosophic thought, Aristotle used his deep appreciation for observable science – biology in particular – to bring a rational, logical rigor to the abstract ideas of his time. He laid key foundational ideas of ‘causality’, and described abstract universals as characteristics that describe what we see in reality, reversing ideas of his predecessor, Plato. He was also the first rigorous ‘ontologist’ – developing categorization structures (including the classic genus-species taxonomy for plants and animals) that help us classify the world around us.
5. Bacon. While not the first in a long empirical tradition, Francis Bacon is typically held up as the earliest catalyst of rigorous thought that established experimental science as a discipline. He provided the building blocks of what would later become known as the scientific method. With this structured approach, man gained the ability to discover and prove the causes of things.
6. Decartes. One of the earliest to fully articulate human self-perception in philosophy, famous for cogito, ergo sum, or “I think, therefore I am” with significant contributions not only in rational philosophy but also in math, where his thinking was foundational in analytical geometry.
7. Hume. Among his many contributions, Hume helped advance the idea of ‘mediation’ in our perceptions, arguing that our logic and conclusions are often filtered, whether by our senses or by our prior patterns of behavior, describing how the mind makes assumptions around causation based on our experiences (note: watch for future discussion of ‘mental heuristics’).
8. Kant. Perhaps the most influential critical thinker of the last 400 years and a rich source of insights, Immanuel Kant brought many of Aristotle’s early notions forward into the modern world. He advanced the categorization of knowledge, with ideas that hinted at ‘context’ based on the notion of “a priori” (pre-existing) factors such as the special external functions of space and time. He also introduced a rational approach to our behavior, bringing logical underpinning to the discussion of ethics.
9. James. Known as the father of modern psychology, William James developed our appreciation for focus, and its importance on perception and discernment.
10. Wittgenstein. Famous for bringing the nuances of language into the discussion of ideas, Wittgenstein argued that both culture and semantic bias carry a fundamental influence in any kind of meaningful exchange. He argued that semantic rigor is essential to philosophical endeavors, serving as a cornerstone of what we now call critical thinking.

At the risk of leaving holes in our story, I’ve left out some key names – deep thinkers like Hegel, Locke, Hobbes, Reid, Mill, and a raft of others – and I’ll take responsibility for the exclusions. This was in part due to space, but also due to the focus of my research on the dynamics and demands of modern collaboration.

If you can help me fill any gaps in the progression, share your thoughts and I’ll provide updates. There’s also a quick survey in the toolbar that would help build a broader consensus on those most influential.

With a foundation in place, where can we go from here?

Unlike any time in history, people and their ideas are getting connected at an accelerated rate. That changes the rules of what’s possible. Critical thinkers who collaborate are likely to drive a potent set of outcomes.

The ability to realize the new dynamics of knowledge sharing may be the next significant challenge our society faces, but also, I believe, it is our greatest promise. Building a sustainable future requires that we relearn what it means to learn, and to advance our ability to learn from each other – globally, deeply, and ever more quickly.

There’s still much work ahead, as this series continues to rediscover what scholars have known all along: the importance of critical thinking.

Let me know your thoughts.