Foundationalism: Can We Know Anything For Certain?

What, if anything, can we know for certain? This is the question that foundationalism has long tried to answer.

Sep 8, 2022By Claire Johnson, BA Philosophy

foundationalism philosophy rene descartes


Foundationalism is a strand of epistemology that says we can only ever know something for certain if somewhere along the line we can trace it back to an undoubtable, irrefutable truth. This truth will serve as the foundation from which all of our other knowledge and beliefs can be built and justified.


Without a foundational truth, the justification for having certain beliefs and knowledge would go on forever in an infinite regress, like the child that repeatedly asks “but why?” until we can no longer give a reasoned answer and most likely conclude “because it just is!”


In this article we will explore the dilemmas that foundationalists face in their attempts to establish undoubtable foundational truths and how they can serve to justify all other knowledge and beliefs about the world.


The Origins of Foundationalism

school of athens aristotle
School of Athens by Raphael, 1511, via Wikimedia Commons.


Foundationalist theories have a long standing history in Philosophical thought. Aristotle was one of the first ancient philosophers to discuss where our knowledge comes from and whether the regress of questions and answers can ever be stopped. In his Posterior Analytics, Aristotle talks in favor of knowledge having foundations to be built upon, claiming that alternative theories either encounter circular reasoning or an infinite regress of reasons.

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I Think Therefore I Am

rene descartes
Rene Descartes, 1650, via National Gallery of Art


More than 1000 years later, when Renes Descartes said “I think therefore I am”, foundationalist philosophers now had one undoubtable truth to work with – that if one can contemplate their existence, then one must surely exist, voilà! All of our knowledge and beliefs now had one indisputable foundation that could serve to justify all of our other beliefs and knowledge about the world.


Foundationalist theories of knowledge have not gone without skepticism. Many Philosophers reject the idea that our own internal experience of thinking is enough to justify all of our subsequent beliefs and knowledge about the world.


Given the arbitrariness of our sensory experiences and ideas of concept, which differ from one person to the next and are often wrong, some philosophers claim that foundationalism would amount to accepting some beliefs as true for no reason at all. This is what anti-foundationalists call The Problem of Arbitrariness (Pollock & Cruz, 1999), and it is this issue that must first be overcome by foundationalists who want to provide a plausible account of how we can ever really know anything with certainty.


Can Foundationalists Escape the Problem of Arbitrariness? 

polyhedron dice ancient
Faience polyhedron inscribed with letters of the Greek alphabet, 2nd–3rd century A.D., via the Met Museum.


Roderick Chisholm attempted to overcome this challenge by redefining what we mean by having a thought and reflecting on an internal thought (Chisholm, 1977).


In his theory, Chisholm says that when a person believes in a proposition or thinks about the world in one way or another, others are of course in a position to ask what reason or justification they have for believing it. In true foundationalist style, Chisholm starts by saying that in order to stop the epistemic regress of justification (but why?) for each proposition, we need a justified belief which is in need of no further justification – something that is evidently and undoubtedly true.


This, he claims, must be non-inferential and basic and will serve as a foundation for the rest of our epistemically justified beliefs (Chisholm, 1977).


We Don’t Know For Certain That the Sky Is Blue, but We Can Know for Certain That We Are Thinking That the Sky Is Blue

starry sky mountains robert caney
Fantastic Mountainous Landscape with a Starry Sky by Robert Caney (1847 – 1911), via the National Gallery of Art.


With inspiration from Descartes, Chisholm claims that a foundational belief is one that is “directly evident” of which thinking and believing are paradigm cases. Consider this exchange between two people:


Person A: “I am thinking about a blue sky.”

Person B: “Well, how do you know this for certain?”

Person A: “Because, as a matter of fact right now, I am currently thinking about a blue sky. The very fact of me saying this means that it is true I am thinking it.”


For Chisholm, the reflection on your internal mental state logically implies the truth of the internal mental state in question. This is what Chisholm calls a self presenting state of affairs (Chisholm, 1977). This differs from this type of exchange:


Person A: “The sky is blue.”

Person B: “Well, how do you know this for certain?”

Person A: “Because it looks blue through my eyes.”

Person B: “But why does it look blue through your eyes…?”


This conversation would go on, each time appealing to other reasons, be it from science or other personal beliefs, to provide justification for each new proposition.


For Chisholm, we don’t know for certain that the sky is blue, but we can know for certain that we are thinking that the sky is blue. These directly evident truths can serve as a foundation for our justified beliefs and knowledge about the world and stop the infinite regress of “well, how do you know this for certain?” (Chisholm, 1977).


Does Chisholm’s Foundationalist Theory Work?

perception drawing
Illustration from Descartes’ A Treatise on the formation of the foetus, Via the Wellcome collection.


Just because we can reflect on an internal belief or thought, does it really mean we are justified for thinking it? And can this really serve as a foundational truth on which we can build all of our other justified beliefs?


This was one criticism offered by Laurence BonJour, who emphasized the importance of epistemic responsibility in the justification of knowledge. Bonjour argued that in order for foundationalism to work, it must escape the two horns of the infamous Sellars Dilemma (BonJour, 1985), which was formulated in Wilfrid Sellars’s essay Empiricism and the Philosophy of Mind.


The Sellars Dilemma

wilfrid sellars
A Young Wilfrid Sellars, via


The Sellars Dilemma aimed to question foundationalist talk of ‘the given.’ ‘The given’ refers to elements of internal experience that foundationalists, like Chisholm, claim are immediately known. For example, if an individual reflects on their internal state “I am thinking about a green golf course”, foundationalists claim it is simply a given that this individual’s experience is true and cannot be doubted. Sellars argues that the idea of the given is purely mythical and only leads to a dilemma about the credibility of these ‘true foundations’ (BonJour, 1985).


To put it simply, The Sellars Dilemma asks: How can a sense-experience play the role of a justifier for all other knowledge?


Laurence BonJour used this dilemma to reject Chisholm’s foundationalism, using the notion of ‘assertive representational content.’ Assertive representational content is the internal content possessed by a person´s hopes, beliefs and fears about the world (BonJour 1985).


For BonJour, a person could have a hope, belief and fear about the same thing; I believe that it is sunny, I hope that it is sunny, I fear that it is sunny. All of these internal states have the same representational content. Chisholm would say that these statements are true simply because they are self presenting states of affairs given by a person that need no further justification.


What If Our Thoughts Are Wrong?

muller lyer lines
The Muller-Lyer illusion, 2020, via Wikimedia Commons.


But what if the representational content of a thought is, in fact, false? Take for instance the Muller-Lyer optical illusion (shown above) where two vertical lines appear to be unequal in length but are in fact the same size. The individual internal experience that the lines are unequal would be false. If Chisholm still claims that the proposition “I believe the lines are unequal in length” is true simply because the individual is undoubtedly having this experience, then Chisholm‘s foundational truths appear paradoxical (Dancy, 1991).


BonJour‘s dilemma is this; either experience has assertive representational content or it doesn’t.  If experience has assertive representational content then a person would need additional justification for thinking that their internal content is correct, and therefore it would not be a foundational truth. (BonJour 1985).


Alternatively, if experience lacks this type of content then according to Chisholm’s foundationalism it cannot provide a valid reason for thinking that a proposition is true (BonJour 1985), for Chisholm claims that truth is in the individual reflecting upon their mental state.


This dilemma is used to argue that any way the view is filled out, it cannot entail that experience is a proper foundation for justification.


Is This the End for Foundationalism?

foundations skyscraper drawing
The Foundations, Building a Skyscraper, by Joseph Pennell, 1910, via the National Gallery of Art.


BonJour was in fact a foundationalist himself, who attempted to create a foundationalist position that could escape the two horns of the dilemma which he used to scrutinize Chisholm. Bonjour makes a distinction between non-reflective (non-apperceptive) awareness of an occurrent belief, and reflective (apperceptive) awareness of a belief (BonJour, 1978).


BonJour says that “awareness of our mental content is a justifying reason for the belief that I have the belief with that very content,” (BonJour 1998). So what does this mean?


BonJour says that an occurrent belief is a belief that an individual has immediate awareness of, simply in virtue of that belief occurring. “To have an occurrent belief is ipso facto to have an awareness of the content of that belief,” (BonJour, 1988). This is akin to Chisholm’s self-presenting truths, since the existence of you believing it makes having the belief undoubtedly true.


But BonJour goes one step further than Chisholm to claim that “the awareness of a belief is non-reflective and not a belief like state,” (BonJour 1998). By claiming that awareness of a thought can be non-reflective, Bonjour can avoid the problems encountered by optical illusions and incorrect thoughts.


Unlike Chisholm who says that the reflection on a thought makes having that thought a certain truth, BonJour’s foundationalism says that even if a person falsely perceives that the optical illusion lines are unequal in length, the non-reflective awareness of the occurrent thought is undoubtable. It does not require further justification since the agent’s instant awareness, before reflecting on whether it is true or not, cannot be mistaken (BonJour 1998).


BonJour’s foundationalism attempts to show that individual experience and reflection itself is not a proper stopping point for the regress of justification in our quest for foundational truths, but rather it is our non reflective, instantly occurring beliefs or perceptions that are foundationally true and undoubtable.


Does BonJour Solve the Problem of Arbitrariness? 

allegorical experience time renaissance
Allegorical Figures of Experience and Time by Giuseppe Maria Mitelli, 1677, via the Met Museum.


BonJour’s theory of foundationalism claims that since the awareness of the specific content is known to the agent simply by virtue of having that experience, then “it turns out to be possible for non-conceptual experience to yield justification for beliefs about the experienced content itself and hence can justify other beliefs’’ (BonJour 1998).


However, many philosophers still question whether we can really have justified knowledge and beliefs about the world simply from information about one’s own non-reflective current state of consciousness. Even without reflection, individual thoughts are highly subjective and Bonjour doesn’t show us how these foundational internal truths can move to justify external truths about the world.


Philosopher Ernest Sosa claimed that BonJour’s foundational truths merely leaves us with a solipsistic view of knowledge and truth, namely that all we can be sure about on this account is that oneself exists.  Sosa claims “there is no way to reason validly from these internal foundations to the external world… forcing us into a radical skepticism that confines us only to knowing our own present consciousness” (Sosa 2003).


Can Knowledge and Truth Be Justified by Other Means?

Coherentist justification, 2002, via Internet Encyclopedia of Philosophy


Unless we are willing to accept that all knowledge about the external world is somehow justified by a foundational truth about our internal mind, it might be that we need to question the concept of justification that foundationalist philosophers are working with.


An alternative view offered by coherentism is that the regress argument is wrong to begin with. Philosophers such as Donald Davidson argue that justification need not be linear and non-holistic. (Dancy, 1991). To put simply, why must we assume that the justification of knowledge travels backwards in a linear fashion to one foundational stopping point?


As Davidson puts it, nothing can count as a reason for a belief except another belief. The fact that our beliefs cohere to other related beliefs can establish their truth, even though each individual belief may lack justification entirely if considered in splendid isolation (Davidson, 1986).


What distinguishes coherentism from foundationalism is that the set of beliefs is the primary bearer of justification. Coherentism says that not all knowledge and justified beliefs rest ultimately on a foundation of non inferential knowledge or justified belief – it is the relationship between these beliefs, none of which are ‘given’ in the way maintained by foundationalists, that serve as justification for our knowledge.


Has Foundationalism Failed?

wisdom conquers ignorance
Wisdom Conquers Ignorance By Bartholomeus Spranger (1546–1611), via the Met Museum.


Coherentism might initially provide a promising solution to some of the deep rooted problems within foundationalist theories. Perhaps, in an intuitive way, it appeals to how we naturally navigate our thoughts about the world around us – as part of a web of related beliefs rather than one irrefutable foundation.


Perhaps Descartes was right – the only thing we can ever know for certain is that I think, therefore I am. But to what capacity we exist, think, reflect and know anything for certain may forever invite the curious child to ask an infinite regress of “but why?” questions.


Perhaps our views on knowledge and truth rest upon whether we think the child deserves a definitive answer, or whether it is better to stay forever curious, adaptable and openminded.




Alston W, Two Types of Foundationalism in Journal of Philosophy vol.71, 1976


BonJour, L.  The Structure of Empirical Knowledge. Cambridge, MA. Harvard University Press 1985


BonJour L Can Empirical Knowledge Have a Foundation? In American Philosophical Quarterly 1978 Vol.15


BonJour L The Dialectic of Foundationalism and Coherentism in The Blackwell Guide to Epistemology. 1998  (Ed. Greco, Sosa) Blackwell Publishing


Chisholm The Directly evident in Theory of Knowledge 1977 (Englewood Cliffs; London)


Davidson, D., “A Coherence Theory of Knowledge and Truth,” in Truth and Interpretation, E. LePore (ed.), Oxford: Blackwell 1986,


Jonathan Dancy, Introduction to Contemporary Epistemology 1ST EDITION, Wiley-Blackwell 1991


Pollock, J and Cruz, J  Contemporary Theories of Knowledge 2nd edition.  New York: Rowman & Littlefield 1999


Sellars, Wilfred,  Does empirical Knowledge Have a Foundation? In Epistemology An anthology 2008 (Ed. Sosa, Kim, Fantl, McGrath) Blackwell


Sosa E Reply to Bonjour in Epistemic Justification 2003 (ed. Sosa, Bonjour) Blackwell

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By Claire JohnsonBA PhilosophyClaire Johnson is a contributing writer in Philosophy and History. She holds a Bachelor's degree in Philosophy from the University of Manchester and has six years of experience in writing about Philosophy and Life Sciences. Claire has traveled across Europe, South East Asia, North America, and Central America to explore different cultures and world views.