Book I: Of Man
Chapter 4: Of Speech
Chapter 5: Of Reason, and Science


Speech was invented, according to Hobbes, for the purpose of putting mental discourse into verbal discourse. There are two benefits gained by this transformation of the mental into the verbal: First, words register a train of thoughts by giving name to the thoughts' conclusions, which can then be remembered without having to reconstruct the train of thoughts continually; second, mental discourse can thus be communicated to other people.

Hobbes identifies four uses of speech:

1) To record knowledge gained of things, which is the acquisition of Arts;

2) To communicate this knowledge to others, which is Counseling or Teaching;

3) To communicate intentions and desires to others and elicit their help; and

4) To entertain ourselves by playing with words.

Hobbes also identifies four abuses of speech:

1) Inconstant signification, in which we carelessly let the meanings of words shift;

2) Metaphorical language, in which we use certain words to mean other words in order to deceive;

3) Lies; and

4) Language employed to injure other people.

Speech is defined in Hobbes's terms as "consisting of Names or Appellations, and their Connexion." Truth and falsehood, which cannot exist outside of speech, are consequent upon the nature of the connection made between names. Truth "consisteth in the right ordering of names in our affirmations," and thus to speak truly—in other words, to speak philosophically—one must use the precise and proper meanings of names. But Hobbes recognizes that we must have some foundational reference for determining whether a meaning is proper and suggests that, following the geometric method, true speech begin by gaining general acceptance of the definitions of its terms. He writes, "In Geometry (which is the onely Science that it hath pleased God hitherto to bestow upon mankind), men begin at settling the significations of their words; which settling of significations, they call Definitions; and place them at the beginning of their reckoning."

Hobbes believes that geometry is a venerable model for a philosophical language because geometry finds its stability in defined terms that everyone has agreed to recognize; therefore, geometric arguments are indisputable. It follows, then, that once philosophical definitions, or first principles, are established, true conclusions can be made by building logically upon prior claims. It is society that determines these first principles of philosophical discourse and true speech, but Hobbes is still faced with the problem of how to achieve social consent for the meanings of words.

Because our experience of the world is mediated by our sensation of it, reality, or objective nature, does not necessarily provide universally satisfying definitions by itself. Hobbes writes, "For though the nature of that we conceive, be the same; yet the diversity of our reception of it, in respect of different constitutions of body, and prejudices of opinion, gives everything a tincture of our different passions. And therefore in reasoning, a man must take heed of words; which besides the signification of what we imagine their nature, have a signification also of the nature, disposition, and interest of the speaker."

Hobbes suggests that the observation of nature and the sensation of the material world is always affected by the individual character of the observer, and therefore experience of natural phenomena and the perception of reality do not constitute an adequate basis upon which to ground philosophically true conclusions to a train of thought.

As long as there persist differences in experience, which in turn correspond to differences in meaning, true certainty cannot be achieved. We cannot simply turn to nature as a basis of truth, for objective nature—nature in itself—is inaccessible to us, always filtered through a screen of subjectivity. Thus, Hobbes decides, there must be some governing body, unanimously recognized, appointed to settle the definitions of words and first principles: "But no one mans Reason, nor the Reason of any one number of men, makes the certaintie; no more than an account is therefore well cast up, because a great many men have unanimously approved it. And therefore, as when there is a controversy in an account, the parties must by their own accord, set up for right Reason, the Reason of some Arbitrator, or Judge, to whose sentence they will both stand, or their controversy must either come to blows, or be undecided, for want of a right Reason constituted by Nature; and so it is also in all debates of what kind soever."

Hobbes points out that there is no "right Reason constituted by Nature," again noting the ineffectiveness of employing nature as the foundation of knowledge. He also points out that the judge who will settle definitions—the definitions upon which everyone agrees to agree—is appointed by the participants "by their own accord." It is this judge (eventually revealed as "the sovereign" in Chapter 18) who then becomes the needed foundation of all knowledge.

Thus, definitions are agreed upon because they are determined by a judge whose decisions everyone has agreed to uphold. With this method for securing the foundation of truth, Hobbes then elaborates his complete program for a reform of philosophy and the institution of a science that will provide secure knowledge and put an end to disagreement and social discord.

The process of science, Hobbes says, is reason, and "Reason . . . is nothing but Reckoning (that is, Adding and Subtracting) of the Consequences of generall names agreed upon." Each step of the reasoning process must itself be secure in its claims, like a carefully wrought object of perfect integrity: "The Use and End of Reason, is not the finding of the summe, and truth of one, or a few consequences, remote from the first definitions, and settled signification of names; but to begin at these; and proceed from one consequence to another. For there can be no certainty of the last Conclusion, without a certainty of all those Affirmation and Negations, on which it was grounded, and inferred." From this mathematical process of philosophical reasoning, with its language of arithmetic and its geometric accretion of consequences and conclusions, one arrives at proper science: "Reason is . . . attayned by Industry; first in apt imposing of Names; and secondly by getting a good and orderly Method in proceeding from the Elements, which are Names, to Assertions made by Connexion of one of them to another; and so to Syllogismes, which are the Connexions of one Assertion to another, till we come to a knowledge of all the Consequences of names appertaining to the subject in hand; and that is it, men call SCIENCE."

This program for a reformed science—"Science, that is, Knowledge of Consequences; which is also called PHILOSOPHY"—produces a geometric, deductive philosophy that is demonstrable to everyone. Accordingly, Hobbes's vision of science maintains that there will be no divisiveness within knowledge because such geometric logic is indisputable; consequently there will be no factions, and ultimately, no civil wars. Hobbes thereby suggests that his approach to science is necessary for the preservation of peace.


By denying the legitimacy of using nature as the foundation of philosophical knowledge, Hobbes issues a direct challenge to natural philosophy as conceived of by Francis Bacon. According to Bacon, natural philosophy should be based on an experimental natural science grounded in natural history. However, Hobbes suggests that nature does not provide secure first principles, and therefore a science grounded in language, rather than nature, is more adequate for making incontrovertible claims. Hobbes's philosophy makes the radical claim that truth is a social construction and argues that its own conclusions are correct precisely because they, too, are socially constructed. When everyone has agreed upon the foundation of knowledge, there is no room for dispute; in contrast, there can be no truth based on an objective nature, for each individual experiences the world differently, and thus the configuration of "reality" is subject to inevitable disagreement and debate.

For Hobbes, eliminating disagreement is essential to eliminating the conditions for civil war; peace is the ultimate purpose of this philosophical program entirely grounded in social consent. At the same time, Hobbes's notion of reality as a social construction contains a certain element of fascism; his notion of an all-powerful judge of definitions, making decisions that cannot be disputed, resembles the fascists' totalitarian philosophy. It advocates the control of reality through power negotiations, but accepts completely the powerlessness of the individual to change that constructed reality.