Academic journal article Journal of the History of Ideas

Galileo's Interventionist Notion of "Cause"

Academic journal article Journal of the History of Ideas

Galileo's Interventionist Notion of "Cause"

Article excerpt

1. INTRODUCTION

In this essay, I shall take up the theme of Galileo's notion of cause, which has already received considerable attention.1 I shall argue that the participants in the debate as it stands have overlooked a striking and essential feature of Galileo's notion of cause. Galileo not only reformed natural philosophy, he also introduced a new notion of causality and integrated it in his scientific practice (hence, this new notion also has its methodological repercussions). Galileo's conception of causality went hand in hand with his methodology (see section 3). Galileo's new notion of causality was closely intertwined with a new conception of how to discover causal relations. His new notion of causality focused on heuristics rather than on ontology. This is the main message of this essay. It is my claim that Galileo was trying to construct a new scientifically useful notion of causality. This new notion of causality is an interventionist notion. According to such a notion, causal relations can be discovered by actively exploring and manipulating natural processes. In order to know nature, we have to intervene in nature. Generally: if we wish to explore whether A is a cause of B, we will need to establish whether deliberate and purposive variations in A result in changes in B. If changes in A produce changes in B, the causal relation is established. It will be shown that this notion first emerged from Galileo's work in hydrostatics and came to full fecundity in his treatment of the tides.

Let me first of all take stock of the present discussion. De Motu, written between 1589 and 1592, is one of Galileo's early scientific works on what we today would roughly call "mechanics." That in De Motu Galileo wished to establish a causal explanation of motion (and acceleration) is accepted by all scholars.2 According to Galileo, falling bodies are moved by an internal cause; projectiles by an external one.3 Galileo indeed claimed that he wished to determine the hidden causes of observable effects "for what we seek are the causes of effects, and these causes are not given to us by experience."4 In dealing with the cause of acceleration, Galileo clarified that he wanted to discover the true, essential and not the accidental cause of acceleration.5 Acceleration is an accidental feature of motion, caused by the gradual overtaking of the intrinsic weight of a body during fall, after being lifted (and the weight being diminished) by an impressed force. Scholars begin to disagree, however, on the presence and importance of causal explanations in the period after this early work. Edwin A. Burtt, echoing Ernst Mach, wrote that Galileo's studies on motion led him to focus more on the how than on the why of motion.6 Closely connected to this is Galileo's ban of final causes from natural philosophy.7 Galileo, according to Burtt, treated motions as the secondary causes of natural phenomena and the forces producing them as their primary causes (of which, further, the nature or essence is unknown).8 We only know quantitative effects of forces in terms of motion.9 This implies that knowledge of primary, essential causes is impossible according to Galileo. After Burtt, authors have gone even further: they questioned the presence of causal explanation in toto in Galileo's (mature) work. On one side of the spectrum, Drake claims that Galileo banished causal inquiries from his science, since they were speculative and unnecessary:

The word cause, frequent in this early book, is less frequent in the later ones. It played little part in Galileo's mature presentation of scientific material, which he confined more and more to observational and mathematical statements.10

Causal claims were present in his early work (e.g. in the Discourse on Floating Bodies [1612]), but not in his mature work, by which Drake apparently means the Dialogo and the Discorsi.11 Pietro Redondi seems to side with Drake: Galileo was defending a docta ignorantia with respect to causes and causal knowledge. …

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