Plato
Plato claims that knowledge is recollection of innate Forms.
Give a counterexample suggesting knowledge can arise from new sensory experience rather than recollection.
Aristotle claims that every natural object has a final cause or purpose.
Give a counterexample of something in nature that seems to lack a purpose.
Descartes holds that clear and distinct perceptions are certain.
Provide a counterexample where something seems clear and distinct but is actually mistaken.
Hume argues that causal reasoning is based on habit, not rational insight.
Provide a counterexample where a causal inference seems grounded in pure reason.
Kant claims space and time are forms of intuition, not properties of things-in-themselves.
Offer a counterexample suggesting space or time might exist independently of human perception.
Plato argues that the Forms are perfect, unchanging realities that ground all knowledge.
Provide a counterexample that challenges the existence of such perfect, universal Forms.
Aristotle argues that virtue lies in the “mean” between extremes.
Provide a counterexample where the virtuous action is not obviously a mean.
Descartes claims the mind is better known than the body.
Offer a counterexample where bodily knowledge seems more certain than introspective knowledge.
Hume denies the existence of a persistent self.
Offer a counterexample suggesting stable personal identity across time.
Kant argues that moral worth depends on acting from duty alone, not inclination.
Provide a counterexample where an action done from inclination appears morally superior to one done from duty.
Plato holds that the soul’s rational part should rule over the appetitive and spirited parts.
Offer a counterexample of a situation where following rational calculation is not clearly better than following emotion or desire.
Aristotle suggests that humans are “rational animals.”
Offer a counterexample where a non-human animal or AI seems to exhibit rationality.
Descartes asserts that the mind is a thinking, non-extended substance.
Give a counterexample challenging the idea of a non-extended mind (e.g., cognition tied to physical processes).
Hume claims all ideas come from impressions.
Provide a counterexample of an idea that appears not to originate from a corresponding impression.
Kant contends that synthetic a priori knowledge is possible (e.g., math).
Give a counterexample challenging the existence of any synthetic a priori truths.
In the Republic, Plato asserts that philosopher-kings, because of their knowledge of the Good, will rule justly.
Give a counterexample showing that philosophical knowledge does not guarantee just political behavior.
Aristotle posits that humans naturally form political communities.
Provide a counterexample indicating that political life might be a contingent choice rather than a natural end.
Descartes argues that God, being benevolent, would not deceive us about the external world.
Provide a counterexample where a benevolent being could have reason to permit pervasive error.
Hume believes you cannot derive an “ought” from an “is.”
Give a counterexample where a normative conclusion seems to follow naturally from a descriptive premise.
Kant asserts that the categorical imperative is universally binding.
Offer a counterexample of a moral situation where universalizing the maxim yields ambiguous or conflicting results.
Plato’s Theory of Forms claims that particulars “participate” in Forms.
Provide a counterexample where participation fails to explain how a property is shared across objects.
Aristotle claims substances are primary and accidents depend on substances.
Give a counterexample where an “accident-like” property seems primary or independent of a substance.
Descartes’ dualism claims that mind and body are distinct substances that interact.
Provide a counterexample or thought experiment showing why interaction is impossible or incoherent.
Hume argues that miracles are always less probable than alternative explanations.
Provide a counterexample scenario where accepting a miracle seems more rational than the alternatives.
Kant claims we can never have knowledge of the noumenal world.
Provide a counterexample suggesting we might gain some knowledge beyond phenomena.