Maclaurin on Spinoza’s Worm in the Blood

In Colin Maclaurin’s four-volume An Account of Sir Issac Newton’s Philosophical Discoveries, published posthumously by his wife Anne, he responds in a footnote to Spinoza’s “Epistle 15,” the so-called “worm in the blood” letter. In Spinoza’s letter he considers how a small animal living in a bloodstream would consider particles to be wholes that the animal whose blood it is would consider to be parts. Spinoza raises a number of interesting conclusions from this, which I won’t go into here.

Maclaurin, a mathematician and philosopher deeply influenced by Newton, denies that human beings can be usefully and correctly compared to such minute animals. Humans, according to Maclaurin’s footnote (Book 1, page 18), “must be allowed to be the first being that pertains to this globe, which, for any thing we know, may be as considerable (not in magnitude, but in more valuable respects) as any in the solar system, which is itself, perhaps, not inferior to any other system in these parts of the vast expanse.” Although with respect to magnitude this planet and its “first being” are not considerable in magnitude, it is appropriate that humans have the particular situation that they do. If they were “occupying a lower place in nature,” they could better understand other minute things but “would have been in no condition to institute an analysis of nature, in that case.” (Maclaurin here seems to conflate being smaller in magnitude with being in a “lower place in nature,” which seems to be the very problem that he justly rejected in the previous two sentences.) On the other side, if we were larger we might have “access to the distant parts of the system,” but this would lead us to “too great attention on” these distant parts. By indulging in a “correspondence with the planets” and then the fixed stars and ultimately infinite space, a person would fail in the duties “incumbent upon him, as a member of society.” Humans are thus properly suited by their magnitude not to fall too easily into investigations of the very small or very large; attempting comprehensive knowledge of either would be detrimental to human society, according to Maclaurin. The trade-off is that we fall short of comprehensive knowledge of the minute and “the distant parts of the system,” but we are able to carry out an “analysis of nature.”

Maclaurin’s footnote is an elaboration and defense of his claim that “tracing the chain of causes is the most noble pursuit of philosophy.” This task begins with what is sensible to us, and those things that are sensible to us are “those things which are proportioned to sense.” He wants to go further, though, and claim that there is something special about our situation such that we are well positioned to carry out this investigation–so well positioned that we can infer a divine appointment. However, Maclaurin’s response to Spinoza is suspicious, seemingly a “just-so” story about our place in a divinely ordained order. Can anything be said on his behalf that doesn’t assume a number of contentious claims about a divine first cause that ordered the universe and situated us just so? In other words, why can’t there be a noble philosophy for the “animalcules in the blood discovered by Microscopes”?

 

Full text of the footnote (in context at this link):

If we were to examine more particularly the situation of man in nature we should find reason to conclude perhaps that it is well adapted to one of his faculties and inclinations for extending his knowledge in such a manner as might be consistent with other duties incumbent upon him and that they have not judged rightly who have compared him in this respect (Spinoz. Epist. 15) with the animalcules in the blood discovered by Microscopes. He must be allowed to be the first being that pertains to this globe which for any thing we know may be as considerable not in magnitude but in more valuable respects as any in the solar system which is itself perhaps not inferior to any other system in these parts of the vast expanse. By occupying a lower place in rature man might have more easily seen what passes amongst the minute particles of matter but he would have lost more than he could have gained by this advantage. He would have been in no condition to institute an analysis of nature in that case. On the other hand we doubt not but there are excellent reasons why he should not have access to the distant parts of the system and must be contented at present with a very imperfect knowledge of them. The duties incumbent upon him as a member of society might have suffered by too great an attention to them or communication with them. Had he been indulged in a correspondence with the planets, he next would have desired to pry into the state of the fixed stars, and at length to comprehend infinite space.