Consensus Theories of Truth

(Rescher, 1993). The meaning of the term itself does not necessarily include the process of maintaining consensus. Consensus might be the result of a direct interaction which aimed to reach consensus, or it might be the agreement of independent individuals.

From the philosophical perspective, consensus is a concept of key importance that has a long history in philosophical debates. One key question in these discussions is: What conclusions can appropriately be drawn in a situation of agreement of individuals? Some philosophers postulate that under specific circumstances and conditions consensus might indicate truth. Consensus theories of truth were influenced by different philosophers (Rescher, 1993). The scope of this dissertation does not allow mentioning all of them; however, the most important contributions will be described and later discussed with

regard to a theoretical foundation for consensus scoring.

Rescher (1993) mentioned several historically significant scholars who supported the idea of accordance between consensus and truth. Ancient theorists such as Aristotle viewed consensus as a supplement to deductive reasoning. These ideas will be addressed first. In contrast, other scholars, such as Jürgen Habermas, John Stuart Mill or Charles Sander Peirce, viewed consensus as the product and result of reason, as a future event that will exist in the long run (Rescher, 1993). The ideas of Jürgen Habermas will be outlined as exemplary for this line of thought.

Aristotle. Aristotle acknowledged the reasoning of a crowd in his Topics (Aristotle, 350 B.C.E), Nicomachean Ethics (Aristotle, 350 B.C.E) and Politics (Aristotle, 350

B.C.E). The consensus omnium is according to Aristotle a valid criterion of truth. Aristotle assigned consensus the status of substantial weight for a specific type of

knowledge or reasoning. In his Topics he differentiated between demonstrative reasoning, dialectical reasoning and contentious reasoning. The first type of reasoning is inferred from true and primary premises and therefore is similar to deductive reasoning. Dialectical reasoning infers from premises grounded on generally accepted knowledge that is true for all or most individuals, or for philosophers. However, Aristotle also accepted the fact that generally accepted opinions might be wrong. In this case, reasoning is contentious. This type of reasoning starts with seemingly generally accepted opinions which prove, however, not to be generally accepted, and are therefore wrong. Hence, this type of reasoning should not be called reasoning, as it only appears to be such.

Habermas. Jürgen Habermas is the most prominent current exponent of the

consensus theory of truth (Hesse, 1978). Habermas assumed that consensus is both the aim and the result of rational thinking and investigation (Habermas, 1984). Instead of claiming that truth can be found experimentally, he discussed the discursive foundation of truth (Healy, 1987). He rejected the idea behind the correspondence theory of truth, namely that truth is based on objective experience. He saw facts as linguistic terms and concluded that

truth must be defined within discursive practice. The consensus theory of truth focuses on the conditions under which truth may be claimed as an outcome. In his 1972 chapter on theories of truth, Habermas states that the potential agreement of all is a condition of truth (Habermas, 1984). The truth of a proposition is defined by the fact that its

discursive claim to validity is irredeemable. However, agreement among individuals does not indicate truth per se. Rational agreement as a result of discourse is suitable as a criterion of truth, whereas random agreement among a group is not.

Consensus is only an indicator of truth if it is the result of an ideal speech situation. The ideal speech situation has four conditions: 1) all potential participants ought to have the same chance of participating in the communication, 2) all participants ought to have the same chance of presenting their views, justifications or explanations, 3) all participants ought to have the same chance of using representative speech acts, that is, acts which refer to the intentions of the individual and 4) all participants ought to have the same chance of using regulative speech acts, such as to order, request, confirm, and so forth. The first and fourth conditions are necessary, though not sufficient for an ideal speech situation. The third condition refers to the truthfulness of the speaker and the second to the possibility to express one’s thoughts freely in the ideal speech situation. These two conditions are

sufficient for an ideal speech situation.

Habermas’ consensus theory of truth has been extensively discussed in the

philosophical literature. Rescher (1993) pointed out the distinction between the empirical reality of consensus and Habermas’ designed hypothetical ideal consensus situation. He concluded that the view of consensus shifted away in Habermas’ theory from de facto consensus to an idealized, non-feasible consensus. Healy (1987) criticized the lack of

reasons for the link between consensus and truth and questioned the status of consensus as a definition (or even weaker criterion) of truth. He concluded that consensus cannot serve as a definition of truth. The circularity of the theory, namely that truth is defined by rational consensus which is itself defined by the ideal speech situation of competent

individuals whose competence is defined by rational consensus, is one of the most widely discussed shortcomings of Habermas’s theory (Beckermann, 1972; Ferrara, 1987). Other critiques concern its relation to the realist correspondence theory of truth. Habermas rejected the correspondence theory, but did not succeed in showing that his consensus theory of truth is non-realistic (Beckermann, 1972). Several assumptions of his theory are grounded in fundamental realist ideas. This inconsistency has also been criticized by other scholars (Ferrara, 1987). Another critical point refers to the theory’s lack of applicability. As Ferrara (1987) pointed out, consensus in science, provided by scientific experts and most widely seen as true, has still been misleading and later proved untrue. Hence, it remains unclear how an ideal speech situation can be attained that guarantees truth in terms of consensus.

Philosophical Concerns about Consensus. According to Rescher (1993) skeptical philosophers like John Lock as well as other philosophers such as Plato and social scientists, have raised concerns about the meaning of consensus. Skeptics question the ability of the human mind on its own to make valid factual claims and reject the

appropriateness of consensus as an indicator of truth. Rescher (1993) himself concluded that consensus is neither a definition nor a criterion of truth, but can at best serve as evidential support for the truth of a proposition. In particular, the consensus of competent experts can give evidence about truth; but, however, consensus in this view provides an epistemological-criteriological utility that is very different from the view that consensus is a functional equivalence of truth.