Version: v1, Published online: 1998
Retrieved April 21, 2021, from https://www.rep.routledge.com/articles/biographical/duns-scotus-john-c-1266-1308/v-1
10. Proof from possibility
To the second objection, that the proof began from contingent premises and thus was not a true demonstration, Scotus replies that his argument for a first efficient cause can be formulated with either existential or modal premises. In the first way, the argument begins with the actual existence of some effect or change and argues directly to the existence of a cause owing to the correlative nature of effect and cause. Formulated in this fashion, the argument is based on contingent but evidently true premises. In the second way, the argument takes its premise from the possibility of some effect and concludes to the possibility of a cause. The actual existence of a first efficient cause is then deduced from its possibility. In this way, the argument can be recast so as to be a necessary demonstration, for the premises are statements not about the actual existence of some effect but about its nature or possibility. Scotus draws out the necessary argument from possibility in the last conclusion concerning efficient cause.
Having answered these two objections, Scotus proceeds to the remaining two of three conclusions necessary to establish a primacy in efficient causality. The second is that the first efficient cause is uncausable, with respect to both its own existence and its ability to cause. As Scotus indicates, this conclusion simply makes explicit the notion of ‘first’ already demonstrated in the arguments against infinite regress. The third and final conclusion is that an efficient cause first in this sense actually exists. As established in the fifth argument against infinite regress, a first efficient cause is possible. Scotus then argues that if such a cause is possible, it must actually exist. If it does not exist, then it could only be possible if some other cause was able to bring it into existence. But such a first efficient cause is absolutely uncausable, so that if it does not actually exist, it is impossible for it to exist. Therefore, if the first efficient cause can exist, it does exist. Alternatively, Scotus says, the same conclusion can be reached by the other traditional arguments recorded against infinite regress, although, as indicated in the above reply to the second objection, they begin from contingent premises.
Dumont, Stephen D.. Proof from possibility. Duns Scotus, John (c.1266–1308), 1998, doi:10.4324/9780415249126-B035-1. Routledge Encyclopedia of Philosophy, Taylor and Francis, https://www.rep.routledge.com/articles/biographical/duns-scotus-john-c-1266-1308/v-1/sections/proof-from-possibility.
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