The world's unsolved problems
993 open questions across 14 fields, gathered from Wikipedia. Pick one and start thinking.
27 results in Philosophy · clear · surprise me
-
Counterfactuals
A statement is a conditional statement with a false antecedent. For example, the statement "If Joseph Swan had not invented the modern incandescent light bulb, then someone else would have invented it anyway" is a counterfactual, because, in fact, Joseph...
Read on Wikipedia → -
Gettier problem
Plato suggests, in his Theaetetus (210a) and Meno (97a–98b), that "knowledge" may be defined as justified true belief. For over two millennia, this definition of knowledge was accepted by subsequent philosophers. An item of information's justifiability,...
Read on Wikipedia → -
Problem of the criterion
The problem of the criterion challenges the traditional definition of knowledge as justified true belief. It questions how one can determine if a justification is sound without relying on further justification, potentially leading to an infinite regress....
Read on Wikipedia → -
Problem of induction
Scottish philosopher David Hume first formulated the problem of induction, arguing there is no non-circular way to justify inductive reasoning. That is, reasoning based on inferring general conclusions from specific observations. This is a problem because...
Read on Wikipedia → -
Molyneux problem
The Molyneux problem dates back to the following question posed by William Molyneux to John Locke in the 17th century: if a man born blind, and able to distinguish by touch between a cube and a globe, were made to see, could he now tell by sight which was...
Read on Wikipedia → -
Münchhausen trilemma
In epistemology, the Münchhausen trilemma is a thought experiment intended to demonstrate the theoretical impossibility of proving any truth, even in the fields of logic and mathematics, without appealing to accepted assumptions. If it is asked how any...
Read on Wikipedia → -
Why there is something rather than nothing
The question about why is there anything at all instead of nothing has been raised or commented on by philosophers including Gottfried Wilhelm Leibniz, Martin Heidegger, and Ludwig Wittgenstein – who called it the fundamental question of metaphysics. The...
Read on Wikipedia → -
Problem of universals
The problem of universals refers to the question of whether properties exist, and if so, what they are. Properties are qualities or relations or names that two or more entities have in common. The various kinds of properties, such as qualities and...
Read on Wikipedia → -
Principle of individuation
Related to the problem of universals, the principle of individuation is what individuates universals.
Read on Wikipedia → -
Sorites paradox
Otherwise known as the "paradox of the heap", the question regards how one defines a "thing." Is a bale of hay still a bale of hay if you remove one straw? If so, is it still a bale of hay if you remove another straw? If you continue this way, you will...
Read on Wikipedia → -
Theseus paradox
Also known as the ship of Theseus, this is a classical paradox on the first branch of metaphysics, ontology (philosophy of existence and identity). The paradox runs thus: There used to be the great ship of Theseus which was made out of, say, 100 parts....
Read on Wikipedia → -
Material implication
People have a rather clear idea of what if-then means. In formal logic however, material implication defines if-then, which is not consistent with the common understanding of conditionals. In formal logic, the statement "If today is Saturday, then 1+1=2"...
Read on Wikipedia → -
Mind–body problem
The mind–body problem is the problem of determining the relationship between the human body and the human mind. Philosophical positions on this question are generally predicated on either a reduction of one to the other, or a belief in the discrete...
Read on Wikipedia → -
Qualia
The question hinges on whether color is a product of the mind or an inherent property of objects. Whilst most philosophers will agree that color assignment corresponds to spectra of light frequencies, it is not at all clear whether the particular...
Read on Wikipedia → -
Hard problem of consciousness
The hard problem of consciousness is the question of what consciousness is and why we have consciousness as opposed to being philosophical zombies. The adjective "hard" is to contrast with the "easy" consciousness problems, which seek to explain the...
Read on Wikipedia → -
Cognition and AI
The philosophy of artificial intelligence and cognition examines the nature and possibility of machine intelligence and consciousness. It intersects with cognitive science, philosophy of mind, and computer science. Major debates concern whether artificial...
Read on Wikipedia → -
Personal identity
In philosophy, the problem of personal identity is concerned with how one is able to identify a single person over a time interval, dealing with such questions as, "What makes it true that a person at one time is the same thing as a person at another...
Read on Wikipedia → -
Mathematical objects
What are numbers, sets, groups, points, etc.? Are they real objects or are they simply relationships that necessarily exist in all structures? Although many disparate views exist regarding what a mathematical object is, the discussion may be roughly...
Read on Wikipedia → -
Demarcation problem
'The problem of demarcation' is an expression introduced by Karl Popper to refer to 'the problem of finding a criterion which would enable us to distinguish between the empirical sciences on the one hand, and mathematics and logic as well as "metaphysical"...
Read on Wikipedia → -
Realism
Does a world independent of human beliefs and representations exist? Is such a world empirically accessible, or would such a world be forever beyond the bounds of human sense and hence unknowable? Can human activity and agency change the objective...
Read on Wikipedia → -
Relationship between science and religion
What is the relationship between science and religion? Philosophers like Paul Feyerabend, A. C. Grayling, and Alvin Plantinga have debated whether they are in conflict, incompatible, incommensurable, or independent.
Read on Wikipedia → -
Existence of God
A variety of arguments including forms of the contingency argument, ontological argument, and moral argument have been proposed by philosophers like Aristotle, Descartes, Leibniz, Gödel, and Aquinas for the existence of God throughout history. Arguments...
Read on Wikipedia → -
Nature of God
What is God like? Philosophers like John Stuart Mill and Aquinas addressed the question of what the nature of God is if God exists. Some of the key disagreements concern the doctrine of impassibility and the coherency of a maximally great being or...
Read on Wikipedia → -
Epistemology of religion
Can religious belief be justified? When? According to the Cambridge Dictionary of Philosophy, religious epistemology "investigates the epistemic status of propositional attitudes about religious claims." Philosophers like Kant, Kierkegaard, William James,...
Read on Wikipedia → -
Most valuable player problem
The concept of the 'most valuable player' is discussed within the field of philosophy of sport. Philosophers Stephen Kershnar and Neil Feit argue that the concept of the MVP is a fundamentally vague concept, but yet valuable in that it promotes the active...
Read on Wikipedia → -
Moral luck
The problem of moral luck is that some people are born into, live within, and experience circumstances that seem to change their moral culpability when all other factors remain the same.
Read on Wikipedia → -
Moral knowledge
Are moral facts possible, what do they consist in, and how do we come to know them? Rightness and wrongness seem to be strange kinds of entities, and different from the usual properties of things in the world, such as wetness, redness, or solidity....
Read on Wikipedia →
Data last refreshed 2026-10-20 03:01 UTC.