Why ‘Common Sense’ Matters in Philosophy?

‘Common sense’ is a notion that philosophers seem unable to work without. They have used it for a variety of purposes. Some use it merely as a more or less neutral term to refer to truisms and platitudes that are widely held, such as that there is a material world external to our minds or that nature can be known by human beings. Others have gone further and used the term in order to make certain claims about it. Immanuel Kant, for example, urged that when we attempt to settle a philosophical dispute, we should never appeal to common sense.

Other claims involving common sense concern its relation to science. Some philosophers have claimed that common sense is at odds with science – that the flip side of scientific progress is the undoing of common sense.1 But others have argued that science, in Gustav Bergmann’s memorable phrase, is ‘the long arm of common sense’ (Bergmann 1957: 20). In one way or another, philosophers had a need to speak of common sense. This introduction shows why and how common sense matters to philosophy, thus lightening up the terrain that subsequent chapters explore in much greater detail. First, we explain briefly what common sense is and, next, what common-sense philosophy is. Then we consider whether, and if so how, common sense should matter to philosophy; can we not do without common sense? Subsequently, we turn to criticisms of the idea that common sense matters to philosophy and criticisms of the very idea of common-sense philosophy. We conclude with a short note on the organization of this article.

What Is Common Sense?

When one tries to pinpoint the referent of ‘common sense’ as the notion is used in the philosophical literature, one will be struck by the fact that it is used to refer to rather different kinds of things: to a particular group of beliefs, to a set of intuitions, to a number of principles, to a belief-forming faculty, and to a loose array of methodological rules. The Greeks used the notion to refer to beliefs that are widely held. That Zeus is the highest god in the pantheon was widely believed in ancient Greece and hence qualifies as a common-sense belief (see Chapter 1 by Richard Bett in this volume). In later times, philosophers wielded a much more restricted notion of common-sense belief.

Thomas Reid, for instance, delineated common-sense beliefs as beliefs that are widely held and that have, in addition, such properties as that their denials are absurd, that they are not believed on the basis of some kind of scientific investigation, and that they are foundational to practices that humans are ineluctably engaged in.2 Take the belief that there is life and intelligence in the people we converse with.

This belief is widely shared, its denial is absurd, it is not based on some form of scientific investigation, and it is foundational to such practices as buying and selling, education, and leading a social life. Hence, this notion of common sense is much more restricted than the notion that the Greeks used. That Zeus is the highest god of the pantheon was once widely believed. But its denial is not absurd, nor is it foundational to a practice that humans are ineluctably engaged in. Therefore, it is not a common-sense belief in Reid’s sense. ‘Common sense’ is also used to refer to certain intuitions that we have.

If we think of intuitions as intellectual seeming, then the following sentences state intellectual intuitions: there presently is a body which is your body (to use an example from G. E. Moore); and no proposition can be true and false at the same time. An intellectual seeming is not necessarily a belief, nor does it necessarily lead to one.

It may intellectually seem to you that velocities are additive, but you do not believe it – at least, not if you are aware of the fact that Einstein’s theory of special relativity entails that velocities are not strictly additive. But no doubt often there is nothing wrong with believing what intellectually seems to be the case; for instance, that the thoughts we are conscious of must have a subject. Here, then, is a common-sense intuition of a proposition, an intuition that leads us to believe it as well. The phrase ‘common sense’ is also used to refer to principles of reasoning and inquiry widely held to be utterly plausible and wholly unproblematic. Examples include:

  • In epistemology: the principle of credulity (‘It is probable that what seems to be the case actually is the case’) and the principle of epistemic conservatism (‘It is unreasonable to revise or alter a belief one has without good reason to do so’);
  • In metaphysics: the principle of parsimony (Occam’s razor: ‘Entities should not be multiplied beyond necessity’), the principle that ‘every change has a cause’, and the principle that ‘everything that begins to exist must have a cause’;
  • In ethics: the principle of double effect (‘There is a morally relevant difference between those consequences of our actions that we intend and those we do not intend but still foresee’), as well as the principle that ‘like cases should be treated equally’;
  • In the philosophy of science: the principle of parsimony (Occam’s razor).

How Does Philosophy Compare to Commonsense?

Philosophy through self examination helps us in its practical and theoretical functions to reach a concept of the universe. Common sense helps science evolve. People’s daily difficulties stir up the need for research, for deepening data interpretation and to propose solutions to overcome the population’s problems.3

What Is Common-sense Philosophy?

In broad strokes, common-sense philosophy is philosophy that is roughly characterized by three methodological features.4

First, it accords common-sense beliefs, intuitions, and principles a strong and privileged epistemic status: roughly speaking, they have authority with default status and should only be given up, if that is possible at all, in the face of extraordinarily strong reasons. (We note that Moore held that no reason is strong enough to force us to give up a common-sense belief: ‘the common sense view of the world’, he said, ‘is in certain fundamental features wholly true’ (Moore (1925) 1993: 110).

Other common-sense philosophers, however, have adopted the idea that common-sense beliefs and intuitions are potentially defensible; they are innocent until proven guilty.)

Second, common-sense philosophy evaluates extant philosophical positions by how well they square with common-sense beliefs, common-sense intuitions, and common-sense principles; if the positions deny, or entail the denial of, common-sense beliefs, intuitions, or principles, then that is decidedly a strike against them.

Third and finally, when not engaged in philosophical critique but in constructive philosophy, common-sense philosophy takes commonsense beliefs, intuitions, and principles as data points that should be given their rightful place.

In Thomas Reid’s view, common sense is the soil on which the flower of philosophy should bloom: ‘Philosophy … has no other root but the principles of Common Sense: it grows out of them, and draws its nourishment from them: severed from this root, its honors wither, its sap is dried up, it dies and rots’ (Reid (1764) 1997: 19). Moore, Chisholm, and other common-sense philosophers concurred: common-sense beliefs and intuitions are data points to be reckoned with, or even starting points for philosophical theorizing.


  1. For various examples of this, see De Ridder et al. (2018); Peels et al. (2020).
  2. Reid ((1785) 2002: 433). For a fuller delineation, see Chapter 7 by René van
    Woudenberg in this volume.
  3. Common Sense, Science And Philosophy: The Links Of Knowledge Necessary For Promoting Health Care (2007) by Ediara Rabello Girão Rios, Kristiane Mesquita Barros Franchi, Raimunda Magalhães da Silva, Rosendo Freitas de Amorim, Nhandeyjara de Carvalho Costa.
  4. Somewhat different characterizations of common-sense philosophy are
    offered by Campbell (1988); Coady (2007); Kelly (2008).

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