Meet the Panelists (01:14)
We assume that events are caused by something, but also support the idea of random chance. Debate moderator Tara Shears introduces philosophy professor Nancy Cartwright, theoretical physics professor Michael Duff, and complex systems professor George Ellis.
Nancy Cartwright: The Pitch (03:41)
Cartwright says that there are unexplained events, according to quantum theory. Photons emitted from de-excited atoms have three energy options. She argues that, although events in engineered experiments can be explained, nearly everything happening to her has unexplained elements, such as her garden wall collapsing.
Michael Duff: The Pitch (03:43)
Duff argues that every effect has a cause. A theory for everything is the central goal of theoretical physics, but has not yet been developed. Evidence from physics shows causality is a valid notion; attempts to negate it lead to theoretical inconsistencies. The Big Bang may be an exception.
George Ellis: The Pitch (03:26)
Ellis agrees that there is randomness at the quantum level, demonstrated by the two slit experiment and radioactive atom decay. Microbiology produces ordered systems from randomness, and we can construct machines with predictable behavior, such as computers. This creates a paradox. He proposes intertwined layers of uncertainty and order.
Theme One: What Makes Things Change? - Part One (05:04)
Cartwright says physics equations are interpreted through real world interactions and distinguishes between causality in physics and causality in the world. She argues that physics does not explain all events, and causality is not deterministic.
What Makes Things Change? - Part Two (06:54)
Duff uses the example of day turning into night to examine how the laws of physics cause change. He does not believe physics explains human consciousness, but all events must be compatible with natural laws. Ellis uses an airplane design example to argue that humans "instruct" physics through engineering and through mental abstract possibilities.
Theme Two: Is Anything ever Random? - Part One (05:05)
Ellis says things are random at a quantum level, but with large enough statistics, quantum randomness obeys statistical laws. Duff accepts quantum mechanics as a probabilistic theory, but says we cannot predict experiment outcomes with certainty. Ellis says statistical behavior is determinant, while individual behavior is not.
Is Anything ever Random? - Part Two (04:16)
In controlled experiments, nature is probabilistic; quantum theory explains probabilities but not individual events. Ellis says the emission of radiation causing cosmic rays to damage DNA and change evolutionary course leading to humanity was an in-deterministic quantum event. Duff says this is not an unexplained event— the Big Bang is an unexplained event.
Theme Three: Abandoning Cause and Effect - Part One (04:49)
Duff cannot imagine a world without cause and effect, because theoretical attempts to do so are problematic. A unified theory of nature involving quantum gravity is also lacking. Cartwright is interested in cause and effect in the social sciences and policy making, and takes issue with causality as having a time order.
Abandoning Cause and Effect - Part Two (06:19)
Ellis believes life would not exist without cause and effect. Function and meaning embodied in higher levels of life direct our actions; physics enables it to happen but does not determine what happens. Duff says a theory of everything would explain physical phenomena, not human consciousness.
Credits: Unexplained Events: Does Everything Have a Cause and Effect? (00:08)
Credits: Unexplained Events: Does Everything Have a Cause and Effect?
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