Eutychianism is a species of monophysitism, the Christological heresy that held that in Christ after the hypostatic union, there is only one nature (physis ). Eutychianism is usually considered to be the strict or authentic type of Monophysitism and is to be distinguished from mitigated forms such as Severian Monophysitism (see severus of antioch). Eutychianism thus understood includes, besides the teaching of eutyches himself, doctrines that his opponents commonly attributed to him as well as similar doctrines of later times, whether or not they claim the patronage of Eutyches or have any historical connection with him. Eutychianism so defined embraces all doctrines in which the immutability of the Eternal Word, or the perfect consubstantial integrity of the human nature in Christ, are attacked or denied.
Eutyches was the recognized leader of the mid-5th-century monks at Constantinople. Not a good theologian, but influential in ecclesiastical politics, he engaged in theological controversy to prevent the revival of nestorianism. His own doctrine came under fire when he was accused of heresy by Bp. Eusebius of Doryleum, the man who had been the accuser of nestorius a generation earlier (431).
Eutyches was condemned by flavian, Patriarch of Constantinople, in the synod of 448. The condemnation was based on Eutyches's refusal to admit that in Christ there are two natures after the union and that Christ's flesh is that "of a man." Eutyches was a friend of cyril of alexandria and slavishly devoted to Cyril's terminology, especially the famous phrase: "one nature of the Incarnate Word." The phrase actually had come from the heretic apollinaris of laodicea, but Cyril had been able to interpret and use it correctly. Eutyches was incapable of this.
Eutyches would admit that Christ was of two natures before the union and that Christ's flesh was consubstantial with that of the Blessed Virgin. He held strongly that Christ was true God and true man. He denied any confusion or change of either nature in the union. But he feared that the statement that there were two natures after the union, or that Christ's flesh was the flesh "of a man," involved admitting two persons in Christ, or Nestorianism. Though reinstated by the Robber Council of ephesus in 449, he was definitively condemned at the Council of chalcedon in 451. He was exiled and thereafter disappears from history.
In the aftermath of opposition to Chalcedon in Egypt and Syria, many doctrines were attributed to Eutyches by his opponents, such as the absorption of Christ's humanity in the divinity, the unreality of Christ's humanity, a heavenly origin of Christ's humanity, the commingling of the humanity and divinity to form a third substance, and transformation of the divinity into the humanity with Christ ceasing to be God. Eutyches did not hold these doctrines, although they did spread among some of the less educated Monophysites. But in refuting them, the orthodox champions often ascribed them to Eutyches himself. The identification of their proponents, except in very few cases, seems to be impossible. Their attribution to Eutyches has no solid foundation. There was more ignorance than malice in his refusal to accept the doctrine of Chalcedon. leo i characterized him as unlearned, unqualified, and imprudent.
Bibliography: r. v. sellers, The Council of Chalcedon (London 1953). p. t. camelot, in a. grillmeier and h. bacht, Das Konzil von Chalkedon: Geschichte und Gegenwart, 3 v. (Würzburg 1951–54) 1:229–242; 2:197–222. b. emmi, Angelicum 29 (1952) 1–42. g. bardy, in a. fliche and v. martin, eds., Histoire de l'égise depuis les origines jusqu'à nos jours (Paris 1935–) 4:211–222. m. jugie, Dictionnaire de théologie catholique, ed. a. vacant et al., 15 v. (Paris 1903–50; Tables générales 1951–) 5.2:1582–1609.