Paul Thagard
Paul Richard Thagard is a Canadian philosopher who specializes in cognitive science, philosophy of mind, and the philosophy of science and medicine. Thagard is a professor emeritus of philosophy at the University of Waterloo. He is a writer, and has contributed to research in analogy and creativity, inference, cognition in the history of science, and the role of emotion in cognition.
In the philosophy of science, Thagard is cited for his work on the use of computational models in explaining conceptual revolutions; his most distinctive contribution to the field is the concept of explanatory coherence, which he has applied to historical cases. He is heavily influenced by pragmatists like C. S. Peirce, and has contributed to the refinement of the idea of inference to the best explanation.
In the philosophy of mind, he is known for his attempts to apply connectionist models of coherence to theories of human thought and action. He is also known for HOTCO, which was his attempt to create a computer model of cognition that incorporated emotions at a fundamental level.
In his general approach to philosophy, Thagard is sharply critical of analytic philosophy for being overly dependent upon intuitions as a source of evidence.
Biography
Thagard was born in Yorkton, Saskatchewan on September 28, 1950. He is a graduate of the Universities of Saskatchewan, Cambridge, Toronto and Michigan.He was Chair of the Governing Board of the Cognitive Science Society, 1998–1999, and President of the Society for Machines and Mentality, 1997–1998. In 2013 he won a Canada Council Killam Prize, and in 1999 was elected a fellow of the Royal Society of Canada. In 2003, he received a University of Waterloo Award for Excellence in Research, and in 2005 he was named a University Research Chair.
Thagard was married to the psychologist Ziva Kunda. Kunda died in 2004.
Philosophical work
Explanatory coherence
Thagard has proposed that many cognitive functions—including perception, analogy, explanation, decision-making, and planning—can be modeled as coherence-based constraint satisfaction processes rather than as purely deductive or probabilistic reasoning.Thagard put forth a formalization of coherence as a constraint satisfaction problem. In this model, coherence operates over a set of representational elements that may either fit together or resist fitting together.
Pairs of elements are linked by either positive or negative constraints. If two elements and cohere, they are connected by a positive constraint ; if they incohere, they are connected by a negative constraint. Constraints are weighted, such that for each constraint there is an associated positive weight.
According to Thagard, coherence maximization involves partitioning elements into accepted and rejected sets so as to satisfy the maximum number, or maximum total weight, of constraints. A positive constraint is satisfied if both elements are accepted or both rejected. A negative constraint is satisfied if one element is accepted and the other rejected. This formulation treats reasoning as a global optimization process over interconnected representations rather than as a sequence of local logical inferences.
Philosophy of science
Thagard worked on the demarcation problem in philosophy of science. Faced with the failure of verifiability and falsifiability, what he called "post positivist depression", he proposed in 1978 a criterion to define pseudoscience, with the broader goal being rescuing science from the relativism of Feyerabend and Rorty. According to Thagard's criterion, "A theory which purports to be scientific is pseudoscientific if and only if":However, in 1988, Thagard wrote that this proposal should "be abandoned," because it had two flaws. Firstly it was hopeless to attempt to find necessary and sufficient conditions for pseudoscience in general, and secondly, the criterion was too soft on astrology which it was specifically meant to brand as pseudoscience. Nonetheless, Thagard, didn't completely abandon his criterion, but instead incorporated it into his new solution to the demarcation problem, which he called "Profile of Science and Pseudoscience", a collection of psychological, historical and logical characteristics, against which a discipline could be compared and categorized as either science or pseudoscience. This process, though not "strict necessary or sufficient", could fulfill the normative goals of science, or what Thagard prefers to call "Natural philosophy", by relying "on descriptions of how everyday and scientific reasoning actually works."
| Science | Pseudoscience |
| Uses correlation thinking. | Uses resemblance thinking. |
| Seeks empirical confirmations. | Neglects empirical matters. |
| Practitioners care about evaluating theories in relation to alternative theories | Practitioners oblivious to alternative theories. |
| Uses highly consilient and simple theories. | Nonsimple theories: many ad hoc hypotheses. |
| Progresses over time: develops new theories that explain new facts. | Stagnant in doctrine and application. |
He describes the Aristotelian realist philosophy of mathematics as "the current philosophy of mathematics that fits best with what is known about minds and science."
Major works
Thagard is the author/co-author of 17 books and over 200 articles.- Dreams, Jokes, and Songs: How Brains Build Consciousness..
- Falsehoods Fly: Why Misinformation Spreads and How to Stop it..
- Balance: How it Works and What it Means..
- Bots and Beasts: What Make Machines, Animals, and People Smart?.
- Brain-Mind: From Neurons to Consciousness and Creativity..
- Mind-Society: From Brains to Social Sciences and Professions..
- The Cognitive Science of Science: Explanation, Discovery, and Conceptual Change..
- The Brain and the Meaning of Life Princeton University Press, 2010 Hot Thought: Mechanisms and Applications of Emotional Cognition Coherence in Thought and Action How Scientists Explain Disease Mind: An Introduction to Cognitive Science Conceptual Revolutions Computational Philosophy of Science
He is also editor of:Philosophy of Psychology and Cognitive Science.