The Skeptics' Guide to the Universe

The Skeptics Guide #1057 - Oct 11 2025

October 11, 2025

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  • The first pig-to-human liver xenotransplant, utilizing a genetically modified pig liver, survived for 171 days in a human recipient before the patient died due to coagulation issues, marking a solid advance in transplant technology. 
  • The 2025 Nobel Prize in Physiology or Medicine was awarded for discoveries concerning peripheral immune tolerance, specifically identifying regulatory T cells (Tregs) which control the immune system outside of the thymus, with implications for treating autoimmune disease and cancer. 
  • A recent Japanese study using PET scans found that adults reporting long COVID brain fog exhibited stronger signals for AMPA receptors (excitatory communication knobs on neurons) across large brain areas, correlating with poorer performance on cognitive tasks. 
  • Modern logicians define deductive reasoning as reasoning that guarantees its conclusion, and inductive reasoning as reasoning that makes the conclusion probable, invalidating the common Aristotelian simplification of universal-to-particular/particular-to-universal. 
  • All scientific reasoning is fundamentally inductive because no scientific conclusion is ever 100% guaranteed, often relying on inference to the best explanation, which can utilize both deductive and inductive steps. 
  • Formal logical fallacies relate to invalid deductive arguments where premises fail to guarantee the conclusion, whereas informal fallacies relate to arguments that fail to provide adequate support, regardless of the conclusion's truth value. 

Segments

Show Logistics and Schedule Change
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(00:00:12)
  • Key Takeaway: The Skeptics’ Guide to the Universe recording schedule has permanently shifted from Wednesdays to Thursdays due to host scheduling adjustments.
  • Summary: The host, Stephen Novella, welcomed the listeners and co-hosts on Thursday, October 9th, 2025. The change to Thursday recording is permanent, primarily to accommodate Kara Santa Maria’s new job schedule. The hosts noted they are now recording in the afternoon rather than the evening.
Pig Liver Xenotransplant Quickie
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(00:03:13)
  • Key Takeaway: A genetically modified pig liver xenograft survived for 171 days in a human recipient in China before the patient died due to coagulation failure, highlighting the complexity of biochemical compatibility beyond immune rejection.
  • Summary: Researchers performed an auxiliary liver xenotransplant using a pig liver with 10 gene edits to address immune and coagulation compatibility. The recipient survived for 171 days, but the ultimate cause of death was gastrointestinal bleeding related to coagulation issues. This procedure is considered a solid advance in xenotransplantation research, which also targets lungs, hearts, and kidneys.
Nobel Prize in Medicine
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(00:07:46)
  • Key Takeaway: Mary E. Brunco, Fred Ramsdell, and Shimon Sakaguchi won the Nobel Prize in Physiology or Medicine for identifying regulatory T cells (Tregs) responsible for peripheral immune tolerance.
  • Summary: The prize recognized the discovery of specific T cell types that keep the immune system in check outside the thymus, preventing self-attack. Shimon Sakaguchi’s work involved removing the thymus in mice, leading to hyperactive immunity until mature T cells containing the CD25 marker were introduced. Brunco and Ramsdell identified the FOXP3 gene mutation responsible for this mechanism in scurfy mice, which corresponds to IPEX syndrome in humans.
Nobel Prize in Physics
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(00:26:53)
  • Key Takeaway: John Clark, Michael Dvore, and John Martinez won the Nobel Prize in Physics for demonstrating that quantum effects like tunneling and energy quantization occur in macroscopic circuits, enabling quantum engineering.
  • Summary: The researchers created superconducting circuits containing Josephson junctions where quantum tunneling—particles passing through energy barriers—was observed macroscopically. They also confirmed energy quantization by observing that microwave photons were absorbed only at discrete, theoretically predicted frequencies. These discoveries provided the foundation for practical quantum technologies like quantum computers and precise sensors.
Nobel Prize in Chemistry
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(00:33:05)
  • Key Takeaway: Susumu Kirigawa, Richard Robson, and Omar Yagi were awarded the Nobel Prize in Chemistry for developing stable and flexible Metal-Organic Frameworks (MOFs) by building upon Robson’s initial structural concepts.
  • Summary: Richard Robson initiated the concept in 1974 by using metal ions and organic molecules as building blocks to create large, porous structures, though his early versions were too fragile. Kirigawa and Yagi independently advanced this by creating more stable and flexible MOFs, which can change shape when filled with substances. MOFs are now used in carbon capture, harvesting water from the air, and as programmable catalysts.
Long COVID Brain Fog Discovery
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(00:44:21)
  • Key Takeaway: A Japanese study found that long COVID patients with cognitive complaints showed increased AMPA receptor signals in their brains, correlating with worse performance on visual memory and picture naming tasks.
  • Summary: Researchers used PET scans with a carbon-11K2 tracer to visualize AMPA receptors, which regulate neuronal firing and can cause excitotoxicity if overactive. The increased receptor signal suggests a disruption in the balance of excitatory signaling within neural networks, potentially explaining symptoms like brain fog. This mechanistic finding moves the diagnosis from a vague syndrome toward a physiological basis, though the research is preliminary.
Podcast Updates and Future Plans
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(00:53:08)
  • Key Takeaway: The Skeptics’ Guide to the Universe team is preparing to launch a new political reality podcast soon and is planning major live events, including a conference in Sydney in July 2026.
  • Summary: The team is finalizing elements for a new podcast, expected to launch within a few weeks. They announced an upcoming trip involving a private show and an extravaganza in Los Angeles, followed by a three-day conference in Sydney, Australia, in partnership with the Australian Skeptics in July 2026. A subsequent conference is also planned for New Zealand the following weekend.
Interview Introduction: David Kyle Johnson
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(01:02:12)
  • Key Takeaway: Philosopher David Kyle Johnson was brought on The Skeptics’ Guide to the Universe to clarify the modern distinction between deductive and inductive reasoning, correcting the common Aristotelian misconception.
  • Summary: The interview addresses a brief prior discussion about Einstein and reasoning types. The common definition—deduction as universal-to-particular and induction as particular-to-universal—is deemed incorrect by modern logicians. The correct modern distinction is that deductive reasoning guarantees its conclusion, whereas inductive reasoning only makes the conclusion probable.
Defining Deduction vs. Induction
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(01:02:44)
  • Key Takeaway: Deductive reasoning guarantees its conclusion, while inductive reasoning only raises the probability of its conclusion.
  • Summary: The common definition of deduction as universal-to-particular reasoning is an inaccurate misconception borrowed from Aristotle. Modern logicians define deduction by its guarantee of conclusion truth, and induction by its probabilistic support. All arguments fall under one of these two categories based on this guarantee criterion.
Examples of Deductive Reasoning
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(01:05:39)
  • Key Takeaway: Deductive arguments include syllogisms (like Modus Ponens) and axiomatic arguments, forming the logical groundwork for modern computing.
  • Summary: Syllogistic reasoning, where premises guarantee the conclusion (e.g., If A=B and B=C, then A=C), exemplifies deduction. Forms like Modus Ponens (If P, then Q; P; therefore Q) are deductive even if they are not universal-to-particular. The development of propositional logic based on this modern understanding of deduction enabled all modern computing.
Examples of Inductive Reasoning
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(01:09:05)
  • Key Takeaway: Inductive reasoning encompasses analogies and inference to the best explanation, and all scientific reasoning is fundamentally inductive.
  • Summary: Inductive arguments raise the probability of a conclusion without guaranteeing it, including methods like analogy (deriving further similarities from shared properties). All science operates inductively because no scientific conclusion is ever 100% proven or guaranteed. Inference to the best explanation is considered the core form of scientific reasoning.
Einstein’s Conflated Terminology
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(01:12:03)
  • Key Takeaway: Einstein incorrectly labeled hypothesis generation and predictive inference as ‘deductive,’ when technically, this process aligns with inductive reasoning.
  • Summary: Einstein used ‘deductive’ to mean making up hypotheses and deducing predictions, which philosophers classify as inductive reasoning (If H, then R; R; therefore H is inductive, not guaranteed deduction). The speaker notes that affirming the consequent (a deductive fallacy) mirrors Einstein’s scientific testing structure, but in science, it provides support, not certainty.
Formal vs. Informal Fallacies
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(01:16:07)
  • Key Takeaway: Formal logical fallacies exclusively deal with deductive arguments being invalid, while informal fallacies deal with inadequate support, meaning the conclusion of an informally fallacious argument can still be true.
  • Summary: Formal fallacies concern arguments where premises fail to guarantee the conclusion, but the conclusion itself is not necessarily false (e.g., affirming the consequent). Informal fallacies fail to provide adequate support, but the conclusion is not guaranteed to be false either. Committing a formal fallacy means the argument structure is invalid, not that the conclusion is factually wrong.
Sherlock Holmes and Abduction
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(01:19:06)
  • Key Takeaway: Sherlock Holmes’s reasoning, often mislabeled as deduction, is best understood as inference to the best explanation, which is a form of induction.
  • Summary: Holmesian reasoning is inference to the best explanation, which is fundamentally inductive because the conclusion is never guaranteed. Abduction, in its original C.S. Peirce definition, refers to hypothesis generation, which precedes inference to the best explanation. Recognizing science as inference to the best explanation broadens scientific thinking beyond just conducting experiments.
Bayes’ Theorem Classification
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(01:28:18)
  • Key Takeaway: Bayes’ theorem presents a philosophical problem: it is inductive due to its probabilistic nature but utilizes deductive mathematical certainty in its calculations.
  • Summary: Bayes’ theorem calculates how data changes the probability of a hypothesis, suggesting it is inductive. However, the underlying mathematical operations (e.g., calculating joint probabilities) follow necessary, deductive rules. The speaker suggests classifying it as ‘deduction in service to induction.’
Science or Fiction Segment
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(01:30:02)
  • Key Takeaway: Quitting smoking after a cancer diagnosis significantly improves survival time, even in advanced stages, contradicting the notion that it is ’too late’ to change outcomes.
  • Summary: The fiction item was that oil and gas companies hold 20% of the world’s renewable energy assets (the actual figure cited was 1.42%). Quitting smoking post-diagnosis more than doubled survival time in advanced-stage cancer patients by reducing the negative impact of carcinogens and improving tolerance to treatment. An avalanche backpack designed to increase airflow around the face was shown in a study to increase survival time by at least five-fold by mitigating asphyxia.