アンナ・ケイ 葉 熙祺

Born in Eresus on the Aegean island of Lesbos, Theophrastus moved to Athens, studying under Plato briefly and then Aristotle, soon becoming the latter’s colleague. In 322/1 BCE he succeeded Aristotle as head of the Lyceum.

The picture arising from his extant works is that of a conscientious scholar and researcher, with a marked emphasis on natural philosophy. His place as Aristotle’s first successor has for a long time created the impression of a dogmatic and docile pupil, but a comparison with his master is invidious.

A more acceptable perspective, established in antiquity (e.g., frag. 72A), is to view his work as trading on the presence of the Aristotelian corpus, while expanding and adjusting even fundamental aspects of the system where required.

Kasumi Arimura
Aristotelian corpus

Exciting recent finds in Arabic and Syriac sources and the new 1992 edition of fragments (edited by Fortenbaugh et al.) have given us a better idea of his learning, independence of thought, and influence (all references to fragments are to 1992).

Diogenes Laertius lists some two hundred titles in the Theophrastan corpus (D.L. 5.42–50), and only a fraction of these works survives. Yet what survives is sufficient to reveal him as a clever and productive philosopher and scientist with wide-ranging interests.

Language and Logic

Theophrastus made contributions to the theory of the syllogism (e.g., on the relation between the second and third figures), and he revised Aristotle’s modal logic, suggesting that the conclusion has the same modality as the weaker premise, not the major premise (a weakest-link principle).

Bali - Bali girl with her "sajeng" temple offering ॐ Bali Floating Leaf Eco-Retreat
Eudemus of Rhodes

He also proposed revising the system of dialectical predication, subsuming the four predicables under definition, perhaps to create “a single universal method”, and he provided us with a definition of the dialectical topos” (not found in Aristotle) as an argumentative strategy or principle.

He is said to have introduced a doctrine of hypothetical syllogisms, possibly in collaboration with Eudemus of Rhodes. True to his reputation as a good speaker, his comments on language advance grammar and style, and he makes a notable effort to use appropriate language in each field.

Physics and Science

Of Theophrastus’s work in the sciences, we still have two major works on plant taxonomy (Enquiry into Plants) and explanations for plants (De causis plantarum [Causes of plants]), famously influential on Carl Linnaeus (1707–1778); nine short tracts on the inanimate (e.g., winds, stones) and physiology (e.g., sweat, dizziness, fatigue); and fragments pertaining to meteorology, biology, epistemology, and psychology.

Physics and Science
Physics and Science

While maintaining an empiricist outlook, Theophrastus consistently dealt with issues of a fundamental nature (frags. 142–143). He added significantly to the scientific methodology developed by Aristotle. The latter sought to describe a system of argumentation, providing the first attempt at a second-order language of research.

This early scientific methodology was a mix of logical principles and rhetorical habits, combining forms of presentation and manipulation with rules of consistency and rigor. Theophrastus also believed in an appropriate method (oikeios tropos) for each field of research (Metaphysics 9a11).

In line with Peripatetic doctrine, Theophrastus attributed teleological order to nature, “which does nothing in vain”, though he allowed for exceptions to this general rule (see the next section).

Carl Linnaeus - Mariya Nagao
Carl Linnaeus

Another feature of Theophrastus’s approach is his readiness to allow for multiple explanations for physical phenomena (found again in Epicurus in different form), which may signal a growing awareness that a universal theory is unattainable.

A correct explanation should give a reason for puzzling facts, be coherent, and harmonize with descriptions of the facts. His views thus adumbrate a principle of falsification.

We can reconstruct significant aspects of Theophrastus’s epistemology and psychology on the basis of mostly late sources, some going back to his own work On the Soul.

Diogenes Laertius
Diogenes Laertius

His empiricist approach is evident in his claims that perception is crucial for knowledge, and that exceptional clarity (to enarges) is a criterion of truth shared by sensation and intellect. Regarding Aristotle’s On the Soul, he asked pertinent questions about the process of sensation (e.g., How does the sense organ become like the object?

The answer is that the organ receives a universal form). His concerns over Aristotle’s notoriously difficult account of intellect (nous) are paraphrased in Themistius (frag. 307A) and the neo-Platonist Priscian (frag. 307B–D).

He asked after the nature of intellect in relation to matter (both seem to be “nothing, but potentially all things”), and puzzled over how intellect and object might affect each other.


Metaphysics - Candice Swanepoel

Theophrastus’s extant short tract on metaphysics, now considered to be a complete work, can be seen as a critical evaluation of Aristotle (and others), in particular, on first principles and the unmoved mover.

He presented a range of connected problems that he did not always clearly resolve. (This is typical of his aporetic [doubtprone] style, in this case perhaps because Metaphysics is an early work or because it is didactic or both.) He also showed himself to be preoccupied with the boundaries of explanation.

For instance, he raised questions about what we can assume as fundamental principles and how many there are, and he looked at possible options (one, more than one) and their problems: A universe with one principle cannot be diverse, but a universe with two or more principles might lack coherence.

fundamental principles
fundamental principles

His discussion of what kind of principles he envisages presents two options: Principles are either the ultimate sources of things (a foundationalist position) or else general laws governing everything (in which case, principles are rules of practice). He restricted the number of principles, and the scope of their influence in the physical realm.

This allowed him to keep certain accidental occurrences (e.g., thunder, but also evil) outside the range of events with a final cause. Theophrastus’s idea of limited teleology and purposiveness (Theophrastus, Metaphysics 7a19–b9, 10a21–23) is confirmed in Arabic sources.

In his botanical works, however, he tried to accommodate anomalies within the Aristotelian framework (De causis plantarum 5). Obviously, Theophrastus’s position complicated the Aristotelian position that “nature does nothing in vain.”



Our material for Theophrastus’s ethical views is rather uneven, ranging from comments on virtue to friendship and natural kinship between animals and humans.

Of interest are the excerpts in Porphyry (c. 300 CE), which discuss forms of sacrifice and reasons for vegetarianism. A lost work on friendship was quite influential, and he seems to have come up with new ideas on emotions (frags. 438–448).


His collection of character sketches (Characters), hugely popular in the eighteenth century, presents psychological profiles in the style of contemporary comedy depicting men with serious character flaws. These profiles perhaps fit into the general framework of Aristotle’s ethics.

Aristotle’s analysis of types (Nicomachean Ethics 2) and his doctrine of virtue as a mean or middle between vices help to understand these flaws as concrete examples of Aristotle’s more abstract model. Some fragments support such a connection. Theophrastus differs from Aristotle at least in focusing on faults and in adopting an anecdotal style of moral instruction.

concrete examples - Ai Okawa
concrete examples
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