Orthoexistence gives greater depth to thething-in-itself without leaving it entirely in itself. Orthoexistencemay be approached via science, though it is not certainthat this way will lead to a thorough understanding. Such a viewgives more way to science, to a scientific insight into existence than Kant's vision does, for it is in the aftermath of present-dayscience in as much as it accepts space and time as being objective.Science tends to delve into the thing-in-itself, to cognizeit, whereas Kant drove it so far from us that we can no longerhope to have an insight into any of its profundities.
By rejecting the objectiveness of space andtime Kant has naturally paved the way for the thing-in-itself.Existence could get free of absurdity to become a thing-in-itself.The problems of the infinite or finite physical space or time are no longer raised for they are pure conceptions.
Kant could not deny existence as a whole,so he abstracted space and time thereof and treated them as apriori intuitions. In this way he thought of the thing-in-itselfin isolation, and focussed on the subject to the detriment of the object. From the existence of the object, the subject is thusonly left the phenomena he deals with, of course, depending onthe initial extrusion of the thing-in itself. According to Kant,we can forget the thing-in-itself because we and the whole bulkof our science deal with phenomena. Otherwise stated, the objectiveworld we are dealing with is the world of phenomena. The thing-in-itself is something singular, which may be of no interest at all as faras we cannot reach it. However, this should not lead to the far-fetchedconclusion that it does not exist for then the whole system wouldcollapse. The thing-in-itself is a ground for any mental schemeand in case we forget it, which is possible, as far as we do notnor can cognize anything about it, we shall nevertheless bear its stamp in our cognitive structures. Indeed, by abstractingspace and time from existence and, hence, by creating the thing-in-itself,we also advance a new mode of cognition whereby man comes witha priori conceptions, like space and time in his sense-perception.The a priori pure reason, i.e. reason before experiment,which is essentially theoretical reason, becomes a leading frameof cognition to be filled with the results of experience whichKant cannot dispense with. The thing-in-itself paved the way fortheoretical, a priori pure reason, whereas phenomenainspire hope in terms of experiment. That is why with Kant, knowledgeis theoretical and experimental. It is obvious that if we forgetthe thing-in-itself and regard phenomena as an objective reality,the cognition professed by Kant is actually modern scientific cognition. The Critique of Pure Reason invites to that theoretical insight which was responsible for the birth of quantummechanics or of such theoretical concepts to which we seek toadapt experimental facts. Additionally, it has made possible increasinglycomplex and refined experiments. In the second edition to The Critique of Pure Reason, Kant explained why he consideredphysics to be a theoretical knowledge of reason. Thus, reasonmust determine the object of physics, he argues. Physicists should understand that "reason only perceives that which it producesafter its own design; that it must not be content to follow, asit were, in the leading-strings of nature, but must proceed inadvance with principles of judgment according to unvarying laws,and compel nature to reply to its questions"⁴.And later on, he added: "It is only the principles of reasonwhich can give to concordant phenomena the validity of laws, andit is only when experiment is directed by these rational principlesthat it can have any real utility. Reason must approach naturewith a view, indeed, of receiving information from it, not, however,in the character of a pupil, who listens to all that his master chooses to tell him, but in that of a judge, who compels his witnessesto reply to those questions which he himself thinks fit to propose"⁵.
Modern science advances no doubt along theselines and finds in Kant one of its spiritual fathers. Kant himself overlooks that phenomena areonly phenomena, and regards them to be objects of research. Thushe finds that the principles for the determination of phenomenain time are⁶ :

1. "All substances, in so far as they can be perceived inspace at the same time, exist in a state of complete reciprocityof action";
   
   
2. "In all changes of phenomena, substanceis permanent, and the quantum thereof in nature is neither increasednor diminished";
   
   
3. "All changes take place accordingto the law of the connection of Cause to Effect".

The thing-in-itself failed to solve the issueof existence, but it has challenged one to re-think it. In thisway Kant unravelled philosophically the breadth of modern science,the role of theoretical languages in approaching reality and the confrontation of theoretical concepts with experience.
Save for the questionable initial solution(which consists in driving space and time from the objective existenceto assign them to the subject alone), Kant's attempt to get outof the deadlock was of fair scientific accuracy.

The Limit of the Thing-in-Itself10